mcs/mcs/ecore.cs

   1 //
   2 // ecore.cs: Core of the Expression representation for the intermediate tree.
   3 //
   4 // Author:
   5 //   Miguel de Icaza (miguel@ximian.com)
   6 //   Marek Safar (marek.safar@seznam.cz)
   7 //
   8 // Copyright 2001, 2002, 2003 Ximian, Inc.
   9 // Copyright 2003-2008 Novell, Inc.
  10 //
  11 //
  12
  13 using System;
  14 using System.Collections.Generic;
  15 using System.Diagnostics;
  16 using System.Reflection;
  17 using System.Reflection.Emit;
  18 using System.Text;
  19 using SLE = System.Linq.Expressions;
  20 using System.Linq;
  21
  22 namespace Mono.CSharp {
  23
  24         /// <remarks>
  25         ///   The ExprClass class contains the is used to pass the
  26         ///   classification of an expression (value, variable, namespace,
  27         ///   type, method group, property access, event access, indexer access,
  28         ///   nothing).
  29         /// </remarks>
  30         public enum ExprClass : byte {
  31                 Unresolved      = 0,
  32
  33                 Value,
  34                 Variable,
  35                 Namespace,
  36                 Type,
  37                 TypeParameter,
  38                 MethodGroup,
  39                 PropertyAccess,
  40                 EventAccess,
  41                 IndexerAccess,
  42                 Nothing,
  43         }
  44
  45         /// <remarks>
  46         ///   This is used to tell Resolve in which types of expressions we're
  47         ///   interested.
  48         /// </remarks>
  49         [Flags]
  50         public enum ResolveFlags {
  51                 // Returns Value, Variable, PropertyAccess, EventAccess or IndexerAccess.
  52                 VariableOrValue         = 1,
  53
  54                 // Returns a type expression.
  55                 Type                    = 1 << 1,
  56
  57                 // Returns a method group.
  58                 MethodGroup             = 1 << 2,
  59
  60                 TypeParameter   = 1 << 3,
  61
  62                 // Mask of all the expression class flags.
  63                 MaskExprClass = VariableOrValue | Type | MethodGroup | TypeParameter,
  64         }
  65
  66         //
  67         // This is just as a hint to AddressOf of what will be done with the
  68         // address.
  69         [Flags]
  70         public enum AddressOp {
  71                 Store = 1,
  72                 Load  = 2,
  73                 LoadStore = 3
  74         };
  75
  76         /// <summary>
  77         ///   This interface is implemented by variables
  78         /// </summary>
  79         public interface IMemoryLocation {
  80                 /// <summary>
  81                 ///   The AddressOf method should generate code that loads
  82                 ///   the address of the object and leaves it on the stack.
  83                 ///
  84                 ///   The `mode' argument is used to notify the expression
  85                 ///   of whether this will be used to read from the address or
  86                 ///   write to the address.
  87                 ///
  88                 ///   This is just a hint that can be used to provide good error
  89                 ///   reporting, and should have no other side effects.
  90                 /// </summary>
  91                 void AddressOf (EmitContext ec, AddressOp mode);
  92         }
  93
  94         //
  95         // An expressions resolved as a direct variable reference
  96         //
  97         public interface IVariableReference : IFixedExpression
  98         {
  99                 bool IsHoisted { get; }
 100                 string Name { get; }
 101                 VariableInfo VariableInfo { get; }
 102
 103                 void SetHasAddressTaken ();
 104         }
 105
 106         //
 107         // Implemented by an expression which could be or is always
 108         // fixed
 109         //
 110         public interface IFixedExpression
 111         {
 112                 bool IsFixed { get; }
 113         }
 114
 115         /// <remarks>
 116         ///   Base class for expressions
 117         /// </remarks>
 118         public abstract class Expression {
 119                 public ExprClass eclass;
 120                 protected TypeSpec type;
 121                 protected Location loc;
 122
 123                 public TypeSpec Type {
 124                         get { return type; }
 125                         set { type = value; }
 126                 }
 127
 128                 public Location Location {
 129                         get { return loc; }
 130                 }
 131
 132                 // Not nice but we have broken hierarchy.
 133                 public virtual void CheckMarshalByRefAccess (ResolveContext ec)
 134                 {
 135                 }
 136
 137                 public virtual string GetSignatureForError ()
 138                 {
 139                         return type.GetDefinition ().GetSignatureForError ();
 140                 }
 141
 142                 public virtual bool IsNull {
 143                         get {
 144                                 return false;
 145                         }
 146                 }
 147
 148                 /// <summary>
 149                 ///   Performs semantic analysis on the Expression
 150                 /// </summary>
 151                 ///
 152                 /// <remarks>
 153                 ///   The Resolve method is invoked to perform the semantic analysis
 154                 ///   on the node.
 155                 ///
 156                 ///   The return value is an expression (it can be the
 157                 ///   same expression in some cases) or a new
 158                 ///   expression that better represents this node.
 159                 ///
 160                 ///   For example, optimizations of Unary (LiteralInt)
 161                 ///   would return a new LiteralInt with a negated
 162                 ///   value.
 163                 ///
 164                 ///   If there is an error during semantic analysis,
 165                 ///   then an error should be reported (using Report)
 166                 ///   and a null value should be returned.
 167                 ///
 168                 ///   There are two side effects expected from calling
 169                 ///   Resolve(): the the field variable "eclass" should
 170                 ///   be set to any value of the enumeration
 171                 ///   `ExprClass' and the type variable should be set
 172                 ///   to a valid type (this is the type of the
 173                 ///   expression).
 174                 /// </remarks>
 175                 protected abstract Expression DoResolve (ResolveContext rc);
 176
 177                 public virtual Expression DoResolveLValue (ResolveContext rc, Expression right_side)
 178                 {
 179                         return null;
 180                 }
 181
 182                 //
 183                 // This is used if the expression should be resolved as a type or namespace name.
 184                 // the default implementation fails.
 185                 //
 186                 public virtual FullNamedExpression ResolveAsTypeStep (IMemberContext rc,  bool silent)
 187                 {
 188                         if (!silent) {
 189                                 ResolveContext ec = new ResolveContext (rc);
 190                                 Expression e = Resolve (ec);
 191                                 if (e != null)
 192                                         e.Error_UnexpectedKind (ec, ResolveFlags.Type, loc);
 193                         }
 194
 195                         return null;
 196                 }
 197
 198                 //
 199                 // C# 3.0 introduced contextual keywords (var) which behaves like a type if type with
 200                 // same name exists or as a keyword when no type was found
 201                 //
 202                 public virtual TypeExpr ResolveAsContextualType (IMemberContext rc, bool silent)
 203                 {
 204                         return ResolveAsTypeTerminal (rc, silent);
 205                 }
 206
 207                 //
 208                 // This is used to resolve the expression as a type, a null
 209                 // value will be returned if the expression is not a type
 210                 // reference
 211                 //
 212                 public virtual TypeExpr ResolveAsTypeTerminal (IMemberContext ec , bool silent)
 213                 {
 214                         int errors = ec.Compiler.Report.Errors;
 215
 216                         FullNamedExpression fne = ResolveAsTypeStep (ec, silent);
 217
 218                         if (fne == null)
 219                                 return null;
 220
 221                         TypeExpr te = fne as TypeExpr;
 222                         if (te == null) {
 223                                 if (!silent && errors == ec.Compiler.Report.Errors)
 224                                         fne.Error_UnexpectedKind (ec.Compiler.Report, null, "type", loc);
 225                                 return null;
 226                         }
 227
 228                         if (!te.CheckAccessLevel (ec)) {
 229                                 ec.Compiler.Report.SymbolRelatedToPreviousError (te.Type);
 230                                 ErrorIsInaccesible (ec, te.Type.GetSignatureForError (), loc);
 231                         }
 232
 233                         te.loc = loc;
 234
 235                         //
 236                         // Obsolete checks cannot be done when resolving base context as they
 237                         // require type dependecies to be set but we are just resolving them
 238                         //
 239                         if (!silent && !(ec is TypeContainer.BaseContext)) {
 240                                 ObsoleteAttribute obsolete_attr = te.Type.GetAttributeObsolete ();
 241                                 if (obsolete_attr != null && !ec.IsObsolete) {
 242                                         AttributeTester.Report_ObsoleteMessage (obsolete_attr, te.GetSignatureForError (), Location, ec.Compiler.Report);
 243                                 }
 244                         }
 245
 246                         return te;
 247                 }
 248
 249                 public static void ErrorIsInaccesible (IMemberContext rc, string member, Location loc)
 250                 {
 251                         rc.Compiler.Report.Error (122, loc, "`{0}' is inaccessible due to its protection level", member);
 252                 }
 253
 254                 public void Error_ExpressionMustBeConstant (ResolveContext rc, Location loc, string e_name)
 255                 {
 256                         rc.Report.Error (133, loc, "The expression being assigned to `{0}' must be constant", e_name);
 257                 }
 258
 259                 public void Error_ConstantCanBeInitializedWithNullOnly (ResolveContext rc, TypeSpec type, Location loc, string name)
 260                 {
 261                         rc.Report.Error (134, loc, "A constant `{0}' of reference type `{1}' can only be initialized with null",
 262                                 name, TypeManager.CSharpName (type));
 263                 }
 264
 265                 public static void Error_InvalidExpressionStatement (Report Report, Location loc)
 266                 {
 267                         Report.Error (201, loc, "Only assignment, call, increment, decrement, and new object " +
 268                                        "expressions can be used as a statement");
 269                 }
 270
 271                 public void Error_InvalidExpressionStatement (BlockContext ec)
 272                 {
 273                         Error_InvalidExpressionStatement (ec.Report, loc);
 274                 }
 275
 276                 public static void Error_VoidInvalidInTheContext (Location loc, Report Report)
 277                 {
 278                         Report.Error (1547, loc, "Keyword `void' cannot be used in this context");
 279                 }
 280
 281                 public virtual void Error_ValueCannotBeConverted (ResolveContext ec, Location loc, TypeSpec target, bool expl)
 282                 {
 283                         Error_ValueCannotBeConvertedCore (ec, loc, target, expl);
 284                 }
 285
 286                 protected void Error_ValueCannotBeConvertedCore (ResolveContext ec, Location loc, TypeSpec target, bool expl)
 287                 {
 288                         // The error was already reported as CS1660
 289                         if (type == InternalType.AnonymousMethod)
 290                                 return;
 291
 292 /*
 293                         if (TypeManager.IsGenericParameter (Type) && TypeManager.IsGenericParameter (target) && type.Name == target.Name) {
 294                                 string sig1 = type.DeclaringMethod == null ?
 295                                         TypeManager.CSharpName (type.DeclaringType) :
 296                                         TypeManager.CSharpSignature (type.DeclaringMethod);
 297                                 string sig2 = target.DeclaringMethod == null ?
 298                                         TypeManager.CSharpName (target.DeclaringType) :
 299                                         TypeManager.CSharpSignature (target.DeclaringMethod);
 300                                 ec.Report.ExtraInformation (loc,
 301                                         String.Format (
 302                                                 "The generic parameter `{0}' of `{1}' cannot be converted to the generic parameter `{0}' of `{2}' (in the previous ",
 303                                                 Type.Name, sig1, sig2));
 304                         } else if (Type.MetaInfo.FullName == target.MetaInfo.FullName) {
 305                                 ec.Report.ExtraInformation (loc,
 306                                         String.Format (
 307                                         "The type `{0}' has two conflicting definitions, one comes from `{1}' and the other from `{2}' (in the previous ",
 308                                         Type.MetaInfo.FullName, Type.Assembly.FullName, target.Assembly.FullName));
 309                         }
 310 */
 311                         if (expl) {
 312                                 ec.Report.Error (30, loc, "Cannot convert type `{0}' to `{1}'",
 313                                         TypeManager.CSharpName (type), TypeManager.CSharpName (target));
 314                                 return;
 315                         }
 316
 317                         ec.Report.DisableReporting ();
 318                         bool expl_exists = Convert.ExplicitConversion (ec, this, target, Location.Null) != null;
 319                         ec.Report.EnableReporting ();
 320
 321                         if (expl_exists) {
 322                                 ec.Report.Error (266, loc, "Cannot implicitly convert type `{0}' to `{1}'. " +
 323                                               "An explicit conversion exists (are you missing a cast?)",
 324                                         TypeManager.CSharpName (Type), TypeManager.CSharpName (target));
 325                                 return;
 326                         }
 327
 328                         ec.Report.Error (29, loc, "Cannot implicitly convert type `{0}' to `{1}'",
 329                                 type.GetSignatureForError (), target.GetSignatureForError ());
 330                 }
 331
 332                 public virtual void Error_VariableIsUsedBeforeItIsDeclared (Report Report, string name)
 333                 {
 334                         Report.Error (841, loc, "A local variable `{0}' cannot be used before it is declared", name);
 335                 }
 336
 337                 public void Error_TypeArgumentsCannotBeUsed (Report report, Location loc, MemberSpec member, int arity)
 338                 {
 339                         // Better message for possible generic expressions
 340                         if (member != null && (member.Kind & MemberKind.GenericMask) != 0) {
 341                                 report.SymbolRelatedToPreviousError (member);
 342                                 if (member is TypeSpec)
 343                                         member = ((TypeSpec) member).GetDefinition ();
 344                                 else
 345                                         member = ((MethodSpec) member).GetGenericMethodDefinition ();
 346
 347                                 string name = member.Kind == MemberKind.Method ? "method" : "type";
 348                                 if (member.IsGeneric) {
 349                                         report.Error (305, loc, "Using the generic {0} `{1}' requires `{2}' type argument(s)",
 350                                                 name, member.GetSignatureForError (), member.Arity.ToString ());
 351                                 } else {
 352                                         report.Error (308, loc, "The non-generic {0} `{1}' cannot be used with the type arguments",
 353                                                 name, member.GetSignatureForError ());
 354                                 }
 355                         } else {
 356                                 Error_TypeArgumentsCannotBeUsed (report, ExprClassName, GetSignatureForError (), loc);
 357                         }
 358                 }
 359
 360                 public void Error_TypeArgumentsCannotBeUsed (Report report, string exprType, string name, Location loc)
 361                 {
 362                         report.Error (307, loc, "The {0} `{1}' cannot be used with type arguments",
 363                                 exprType, name);
 364                 }
 365
 366                 protected virtual void Error_TypeDoesNotContainDefinition (ResolveContext ec, TypeSpec type, string name)
 367                 {
 368                         Error_TypeDoesNotContainDefinition (ec, loc, type, name);
 369                 }
 370
 371                 public static void Error_TypeDoesNotContainDefinition (ResolveContext ec, Location loc, TypeSpec type, string name)
 372                 {
 373                         ec.Report.SymbolRelatedToPreviousError (type);
 374                         ec.Report.Error (117, loc, "`{0}' does not contain a definition for `{1}'",
 375                                 TypeManager.CSharpName (type), name);
 376                 }
 377
 378                 protected static void Error_ValueAssignment (ResolveContext ec, Location loc)
 379                 {
 380                         ec.Report.Error (131, loc, "The left-hand side of an assignment must be a variable, a property or an indexer");
 381                 }
 382
 383                 public ResolveFlags ExprClassToResolveFlags {
 384                         get {
 385                                 switch (eclass) {
 386                                 case ExprClass.Type:
 387                                 case ExprClass.Namespace:
 388                                         return ResolveFlags.Type;
 389
 390                                 case ExprClass.MethodGroup:
 391                                         return ResolveFlags.MethodGroup;
 392
 393                                 case ExprClass.TypeParameter:
 394                                         return ResolveFlags.TypeParameter;
 395
 396                                 case ExprClass.Value:
 397                                 case ExprClass.Variable:
 398                                 case ExprClass.PropertyAccess:
 399                                 case ExprClass.EventAccess:
 400                                 case ExprClass.IndexerAccess:
 401                                         return ResolveFlags.VariableOrValue;
 402
 403                                 default:
 404                                         throw new InternalErrorException (loc.ToString () + " " +  GetType () + " ExprClass is Invalid after resolve");
 405                                 }
 406                         }
 407                 }
 408
 409                 /// <summary>
 410                 ///   Resolves an expression and performs semantic analysis on it.
 411                 /// </summary>
 412                 ///
 413                 /// <remarks>
 414                 ///   Currently Resolve wraps DoResolve to perform sanity
 415                 ///   checking and assertion checking on what we expect from Resolve.
 416                 /// </remarks>
 417                 public Expression Resolve (ResolveContext ec, ResolveFlags flags)
 418                 {
 419                         if (eclass != ExprClass.Unresolved)
 420                                 return this;
 421
 422                         Expression e;
 423                         try {
 424                                 e = DoResolve (ec);
 425
 426                                 if (e == null)
 427                                         return null;
 428
 429                                 if ((flags & e.ExprClassToResolveFlags) == 0) {
 430                                         e.Error_UnexpectedKind (ec, flags, loc);
 431                                         return null;
 432                                 }
 433
 434                                 if (e.type == null)
 435                                         throw new InternalErrorException ("Expression `{0}' didn't set its type in DoResolve", e.GetType ());
 436
 437                                 return e;
 438                         } catch (Exception ex) {
 439                                 if (loc.IsNull || Report.DebugFlags > 0 || ex is CompletionResult || ec.Report.IsDisabled)
 440                                         throw;
 441
 442                                 ec.Report.Error (584, loc, "Internal compiler error: {0}", ex.Message);
 443                                 return EmptyExpression.Null;
 444                         }
 445                 }
 446
 447                 /// <summary>
 448                 ///   Resolves an expression and performs semantic analysis on it.
 449                 /// </summary>
 450                 public Expression Resolve (ResolveContext rc)
 451                 {
 452                         return Resolve (rc, ResolveFlags.VariableOrValue | ResolveFlags.MethodGroup);
 453                 }
 454
 455                 /// <summary>
 456                 ///   Resolves an expression for LValue assignment
 457                 /// </summary>
 458                 ///
 459                 /// <remarks>
 460                 ///   Currently ResolveLValue wraps DoResolveLValue to perform sanity
 461                 ///   checking and assertion checking on what we expect from Resolve
 462                 /// </remarks>
 463                 public Expression ResolveLValue (ResolveContext ec, Expression right_side)
 464                 {
 465                         int errors = ec.Report.Errors;
 466                         bool out_access = right_side == EmptyExpression.OutAccess.Instance;
 467
 468                         Expression e = DoResolveLValue (ec, right_side);
 469
 470                         if (e != null && out_access && !(e is IMemoryLocation)) {
 471                                 // FIXME: There's no problem with correctness, the 'Expr = null' handles that.
 472                                 //        Enabling this 'throw' will "only" result in deleting useless code elsewhere,
 473
 474                                 //throw new InternalErrorException ("ResolveLValue didn't return an IMemoryLocation: " +
 475                                 //                                e.GetType () + " " + e.GetSignatureForError ());
 476                                 e = null;
 477                         }
 478
 479                         if (e == null) {
 480                                 if (errors == ec.Report.Errors) {
 481                                         if (out_access)
 482                                                 ec.Report.Error (1510, loc, "A ref or out argument must be an assignable variable");
 483                                         else
 484                                                 Error_ValueAssignment (ec, loc);
 485                                 }
 486                                 return null;
 487                         }
 488
 489                         if (e.eclass == ExprClass.Unresolved)
 490                                 throw new Exception ("Expression " + e + " ExprClass is Invalid after resolve");
 491
 492                         if ((e.type == null) && !(e is GenericTypeExpr))
 493                                 throw new Exception ("Expression " + e + " did not set its type after Resolve");
 494
 495                         return e;
 496                 }
 497
 498                 public virtual void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
 499                 {
 500                         rc.Compiler.Report.Error (182, loc,
 501                                 "An attribute argument must be a constant expression, typeof expression or array creation expression");
 502                 }
 503
 504                 /// <summary>
 505                 ///   Emits the code for the expression
 506                 /// </summary>
 507                 ///
 508                 /// <remarks>
 509                 ///   The Emit method is invoked to generate the code
 510                 ///   for the expression.
 511                 /// </remarks>
 512                 public abstract void Emit (EmitContext ec);
 513
 514
 515                 // Emit code to branch to @target if this expression is equivalent to @on_true.
 516                 // The default implementation is to emit the value, and then emit a brtrue or brfalse.
 517                 // Subclasses can provide more efficient implementations, but those MUST be equivalent,
 518                 // including the use of conditional branches.  Note also that a branch MUST be emitted
 519                 public virtual void EmitBranchable (EmitContext ec, Label target, bool on_true)
 520                 {
 521                         Emit (ec);
 522                         ec.Emit (on_true ? OpCodes.Brtrue : OpCodes.Brfalse, target);
 523                 }
 524
 525                 // Emit this expression for its side effects, not for its value.
 526                 // The default implementation is to emit the value, and then throw it away.
 527                 // Subclasses can provide more efficient implementations, but those MUST be equivalent
 528                 public virtual void EmitSideEffect (EmitContext ec)
 529                 {
 530                         Emit (ec);
 531                         ec.Emit (OpCodes.Pop);
 532                 }
 533
 534                 /// <summary>
 535                 ///   Protected constructor.  Only derivate types should
 536                 ///   be able to be created
 537                 /// </summary>
 538
 539                 protected Expression ()
 540                 {
 541                 }
 542
 543                 /// <summary>
 544                 ///   Returns a fully formed expression after a MemberLookup
 545                 /// </summary>
 546                 ///
 547                 static Expression ExprClassFromMemberInfo (MemberSpec spec, Location loc)
 548                 {
 549                         if (spec is EventSpec)
 550                                 return new EventExpr ((EventSpec) spec, loc);
 551                         if (spec is ConstSpec)
 552                                 return new ConstantExpr ((ConstSpec) spec, loc);
 553                         if (spec is FieldSpec)
 554                                 return new FieldExpr ((FieldSpec) spec, loc);
 555                         if (spec is PropertySpec)
 556                                 return new PropertyExpr ((PropertySpec) spec, loc);
 557                         if (spec is TypeSpec)
 558                                 return new TypeExpression (((TypeSpec) spec), loc);
 559
 560                         return null;
 561                 }
 562
 563                 protected static MethodSpec ConstructorLookup (ResolveContext rc, TypeSpec type, ref Arguments args, Location loc)
 564                 {
 565                         var ctors = MemberCache.FindMembers (type, ConstructorInfo.ConstructorName, true);
 566                         if (ctors == null) {
 567                                 rc.Report.SymbolRelatedToPreviousError (type);
 568                                 if (type.IsStruct) {
 569                                         // Report meaningful error for struct as they always have default ctor in C# context
 570                                         OverloadResolver.Error_ConstructorMismatch (rc, type, args == null ? 0 : args.Count, loc);
 571                                 } else {
 572                                         rc.Report.Error (143, loc, "The class `{0}' has no constructors defined",
 573                                                 type.GetSignatureForError ());
 574                                 }
 575
 576                                 return null;
 577                         }
 578
 579                         var r = new OverloadResolver (ctors, OverloadResolver.Restrictions.NoBaseMembers, loc);
 580                         return r.ResolveMember<MethodSpec> (rc, ref args);
 581                 }
 582
 583                 //
 584                 // Lookup type `queried_type' for code in class `container_type' with a qualifier of
 585                 // `qualifier_type' or null to lookup members in the current class.
 586                 //
 587                 public static Expression MemberLookup (ResolveContext rc, TypeSpec currentType, TypeSpec queried_type, string name, int arity, bool invocableOnly, Location loc)
 588                 {
 589                         var members = MemberCache.FindMembers (queried_type, name, false);
 590                         if (members == null)
 591                                 return null;
 592
 593                         MemberSpec non_method = null;
 594                         MemberSpec ambig_non_method = null;
 595                         currentType = currentType ?? InternalType.FakeInternalType;
 596                         do {
 597                                 for (int i = 0; i < members.Count; ++i) {
 598                                         var member = members[i];
 599
 600                                         // HACK: for events because +=/-= can appear at same class only, should use OverrideToBase there
 601                                         if ((member.Modifiers & Modifiers.OVERRIDE) != 0 && member.Kind != MemberKind.Event)
 602                                                 continue;
 603
 604                                         if (arity > 0 && member.Arity != arity)
 605                                                 continue;
 606
 607                                         if (rc != null && !member.IsAccessible (currentType))
 608                                                 continue;
 609
 610                                         if (invocableOnly) {
 611                                                 if (member is MethodSpec)
 612                                                         return new MethodGroupExpr (members, queried_type, loc);
 613
 614                                                 if (!Invocation.IsMemberInvocable (member))
 615                                                         continue;
 616                                         }
 617
 618                                         if (non_method == null || member is MethodSpec) {
 619                                                 non_method = member;
 620                                         } else if (currentType != null) {
 621                                                 ambig_non_method = member;
 622                                         }
 623                                 }
 624
 625                                 if (non_method != null) {
 626                                         if (ambig_non_method != null && rc != null) {
 627                                                 rc.Report.SymbolRelatedToPreviousError (non_method);
 628                                                 rc.Report.SymbolRelatedToPreviousError (ambig_non_method);
 629                                                 rc.Report.Error (229, loc, "Ambiguity between `{0}' and `{1}'",
 630                                                         non_method.GetSignatureForError (), ambig_non_method.GetSignatureForError ());
 631                                         }
 632
 633                                         if (non_method is MethodSpec)
 634                                                 return new MethodGroupExpr (members, queried_type, loc);
 635
 636                                         return ExprClassFromMemberInfo (non_method, loc);
 637                                 }
 638
 639                                 if (members[0].DeclaringType.BaseType == null)
 640                                         members = null;
 641                                 else
 642                                         members = MemberCache.FindMembers (members[0].DeclaringType.BaseType, name, false);
 643
 644                         } while (members != null);
 645
 646                         return null;
 647                 }
 648
 649                 protected virtual void Error_NegativeArrayIndex (ResolveContext ec, Location loc)
 650                 {
 651                         throw new NotImplementedException ();
 652                 }
 653
 654                 protected void Error_PointerInsideExpressionTree (ResolveContext ec)
 655                 {
 656                         ec.Report.Error (1944, loc, "An expression tree cannot contain an unsafe pointer operation");
 657                 }
 658
 659                 /// <summary>
 660                 ///   Returns an expression that can be used to invoke operator true
 661                 ///   on the expression if it exists.
 662                 /// </summary>
 663                 protected static Expression GetOperatorTrue (ResolveContext ec, Expression e, Location loc)
 664                 {
 665                         return GetOperatorTrueOrFalse (ec, e, true, loc);
 666                 }
 667
 668                 /// <summary>
 669                 ///   Returns an expression that can be used to invoke operator false
 670                 ///   on the expression if it exists.
 671                 /// </summary>
 672                 static public Expression GetOperatorFalse (ResolveContext ec, Expression e, Location loc)
 673                 {
 674                         return GetOperatorTrueOrFalse (ec, e, false, loc);
 675                 }
 676
 677                 static Expression GetOperatorTrueOrFalse (ResolveContext ec, Expression e, bool is_true, Location loc)
 678                 {
 679                         var op = is_true ? Operator.OpType.True : Operator.OpType.False;
 680                         var methods = MemberCache.GetUserOperator (e.type, op, false);
 681                         if (methods == null)
 682                                 return null;
 683
 684                         Arguments arguments = new Arguments (1);
 685                         arguments.Add (new Argument (e));
 686
 687                         var res = new OverloadResolver (methods, OverloadResolver.Restrictions.NoBaseMembers, loc);
 688                         var oper = res.ResolveOperator (ec, ref arguments);
 689
 690                         if (oper == null)
 691                                 return null;
 692
 693                         return new UserOperatorCall (oper, arguments, null, loc);
 694                 }
 695
 696                 public virtual string ExprClassName
 697                 {
 698                         get {
 699                                 switch (eclass){
 700                                 case ExprClass.Unresolved:
 701                                         return "Unresolved";
 702                                 case ExprClass.Value:
 703                                         return "value";
 704                                 case ExprClass.Variable:
 705                                         return "variable";
 706                                 case ExprClass.Namespace:
 707                                         return "namespace";
 708                                 case ExprClass.Type:
 709                                         return "type";
 710                                 case ExprClass.MethodGroup:
 711                                         return "method group";
 712                                 case ExprClass.PropertyAccess:
 713                                         return "property access";
 714                                 case ExprClass.EventAccess:
 715                                         return "event access";
 716                                 case ExprClass.IndexerAccess:
 717                                         return "indexer access";
 718                                 case ExprClass.Nothing:
 719                                         return "null";
 720                                 case ExprClass.TypeParameter:
 721                                         return "type parameter";
 722                                 }
 723                                 throw new Exception ("Should not happen");
 724                         }
 725                 }
 726
 727                 /// <summary>
 728                 ///   Reports that we were expecting `expr' to be of class `expected'
 729                 /// </summary>
 730                 public void Error_UnexpectedKind (Report r, MemberCore mc, string expected, Location loc)
 731                 {
 732                         Error_UnexpectedKind (r, mc, expected, ExprClassName, loc);
 733                 }
 734
 735                 public void Error_UnexpectedKind (Report r, MemberCore mc, string expected, string was, Location loc)
 736                 {
 737                         string name;
 738                         if (mc != null)
 739                                 name = mc.GetSignatureForError ();
 740                         else
 741                                 name = GetSignatureForError ();
 742
 743                         r.Error (118, loc, "`{0}' is a `{1}' but a `{2}' was expected",
 744                               name, was, expected);
 745                 }
 746
 747                 public void Error_UnexpectedKind (ResolveContext ec, ResolveFlags flags, Location loc)
 748                 {
 749                         string [] valid = new string [4];
 750                         int count = 0;
 751
 752                         if ((flags & ResolveFlags.VariableOrValue) != 0) {
 753                                 valid [count++] = "variable";
 754                                 valid [count++] = "value";
 755                         }
 756
 757                         if ((flags & ResolveFlags.Type) != 0)
 758                                 valid [count++] = "type";
 759
 760                         if ((flags & ResolveFlags.MethodGroup) != 0)
 761                                 valid [count++] = "method group";
 762
 763                         if (count == 0)
 764                                 valid [count++] = "unknown";
 765
 766                         StringBuilder sb = new StringBuilder (valid [0]);
 767                         for (int i = 1; i < count - 1; i++) {
 768                                 sb.Append ("', `");
 769                                 sb.Append (valid [i]);
 770                         }
 771                         if (count > 1) {
 772                                 sb.Append ("' or `");
 773                                 sb.Append (valid [count - 1]);
 774                         }
 775
 776                         ec.Report.Error (119, loc,
 777                                 "Expression denotes a `{0}', where a `{1}' was expected", ExprClassName, sb.ToString ());
 778                 }
 779
 780                 public static void UnsafeError (ResolveContext ec, Location loc)
 781                 {
 782                         UnsafeError (ec.Report, loc);
 783                 }
 784
 785                 public static void UnsafeError (Report Report, Location loc)
 786                 {
 787                         Report.Error (214, loc, "Pointers and fixed size buffers may only be used in an unsafe context");
 788                 }
 789
 790
 791                 //
 792                 // Returns the size of type `t' if known, otherwise, 0
 793                 //
 794                 public static int GetTypeSize (TypeSpec t)
 795                 {
 796                         if (t == TypeManager.int32_type ||
 797                             t == TypeManager.uint32_type ||
 798                             t == TypeManager.float_type)
 799                                 return 4;
 800                         else if (t == TypeManager.int64_type ||
 801                                  t == TypeManager.uint64_type ||
 802                                  t == TypeManager.double_type)
 803                                 return 8;
 804                         else if (t == TypeManager.byte_type ||
 805                                  t == TypeManager.sbyte_type ||
 806                                  t == TypeManager.bool_type)
 807                                 return 1;
 808                         else if (t == TypeManager.short_type ||
 809                                  t == TypeManager.char_type ||
 810                                  t == TypeManager.ushort_type)
 811                                 return 2;
 812                         else if (t == TypeManager.decimal_type)
 813                                 return 16;
 814                         else
 815                                 return 0;
 816                 }
 817
 818                 protected void Error_CannotModifyIntermediateExpressionValue (ResolveContext ec)
 819                 {
 820                         ec.Report.SymbolRelatedToPreviousError (type);
 821                         if (ec.CurrentInitializerVariable != null) {
 822                                 ec.Report.Error (1918, loc, "Members of value type `{0}' cannot be assigned using a property `{1}' object initializer",
 823                                         TypeManager.CSharpName (type), GetSignatureForError ());
 824                         } else {
 825                                 ec.Report.Error (1612, loc, "Cannot modify a value type return value of `{0}'. Consider storing the value in a temporary variable",
 826                                         GetSignatureForError ());
 827                         }
 828                 }
 829
 830                 //
 831                 // Converts `source' to an int, uint, long or ulong.
 832                 //
 833                 protected Expression ConvertExpressionToArrayIndex (ResolveContext ec, Expression source)
 834                 {
 835                         if (source.type == InternalType.Dynamic) {
 836                                 Arguments args = new Arguments (1);
 837                                 args.Add (new Argument (source));
 838                                 return new DynamicConversion (TypeManager.int32_type, CSharpBinderFlags.ConvertArrayIndex, args, loc).Resolve (ec);
 839                         }
 840
 841                         Expression converted;
 842
 843                         using (ec.Set (ResolveContext.Options.CheckedScope)) {
 844                                 converted = Convert.ImplicitConversion (ec, source, TypeManager.int32_type, source.loc);
 845                                 if (converted == null)
 846                                         converted = Convert.ImplicitConversion (ec, source, TypeManager.uint32_type, source.loc);
 847                                 if (converted == null)
 848                                         converted = Convert.ImplicitConversion (ec, source, TypeManager.int64_type, source.loc);
 849                                 if (converted == null)
 850                                         converted = Convert.ImplicitConversion (ec, source, TypeManager.uint64_type, source.loc);
 851
 852                                 if (converted == null) {
 853                                         source.Error_ValueCannotBeConverted (ec, source.loc, TypeManager.int32_type, false);
 854                                         return null;
 855                                 }
 856                         }
 857
 858                         //
 859                         // Only positive constants are allowed at compile time
 860                         //
 861                         Constant c = converted as Constant;
 862                         if (c != null && c.IsNegative)
 863                                 Error_NegativeArrayIndex (ec, source.loc);
 864
 865                         // No conversion needed to array index
 866                         if (converted.Type == TypeManager.int32_type)
 867                                 return converted;
 868
 869                         return new ArrayIndexCast (converted).Resolve (ec);
 870                 }
 871
 872                 //
 873                 // Derived classes implement this method by cloning the fields that
 874                 // could become altered during the Resolve stage
 875                 //
 876                 // Only expressions that are created for the parser need to implement
 877                 // this.
 878                 //
 879                 protected virtual void CloneTo (CloneContext clonectx, Expression target)
 880                 {
 881                         throw new NotImplementedException (
 882                                 String.Format (
 883                                         "CloneTo not implemented for expression {0}", this.GetType ()));
 884                 }
 885
 886                 //
 887                 // Clones an expression created by the parser.
 888                 //
 889                 // We only support expressions created by the parser so far, not
 890                 // expressions that have been resolved (many more classes would need
 891                 // to implement CloneTo).
 892                 //
 893                 // This infrastructure is here merely for Lambda expressions which
 894                 // compile the same code using different type values for the same
 895                 // arguments to find the correct overload
 896                 //
 897                 public Expression Clone (CloneContext clonectx)
 898                 {
 899                         Expression cloned = (Expression) MemberwiseClone ();
 900                         CloneTo (clonectx, cloned);
 901
 902                         return cloned;
 903                 }
 904
 905                 //
 906                 // Implementation of expression to expression tree conversion
 907                 //
 908                 public abstract Expression CreateExpressionTree (ResolveContext ec);
 909
 910                 protected Expression CreateExpressionFactoryCall (ResolveContext ec, string name, Arguments args)
 911                 {
 912                         return CreateExpressionFactoryCall (ec, name, null, args, loc);
 913                 }
 914
 915                 protected Expression CreateExpressionFactoryCall (ResolveContext ec, string name, TypeArguments typeArguments, Arguments args)
 916                 {
 917                         return CreateExpressionFactoryCall (ec, name, typeArguments, args, loc);
 918                 }
 919
 920                 public static Expression CreateExpressionFactoryCall (ResolveContext ec, string name, TypeArguments typeArguments, Arguments args, Location loc)
 921                 {
 922                         return new Invocation (new MemberAccess (CreateExpressionTypeExpression (ec, loc), name, typeArguments, loc), args);
 923                 }
 924
 925                 protected static TypeExpr CreateExpressionTypeExpression (ResolveContext ec, Location loc)
 926                 {
 927                         TypeExpr texpr = TypeManager.expression_type_expr;
 928                         if (texpr == null) {
 929                                 TypeSpec t = TypeManager.CoreLookupType (ec.Compiler, "System.Linq.Expressions", "Expression", MemberKind.Class, true);
 930                                 if (t == null)
 931                                         return null;
 932
 933                                 TypeManager.expression_type_expr = texpr = new TypeExpression (t, Location.Null);
 934                         }
 935
 936                         return texpr;
 937                 }
 938
 939                 //
 940                 // Implemented by all expressions which support conversion from
 941                 // compiler expression to invokable runtime expression. Used by
 942                 // dynamic C# binder.
 943                 //
 944                 public virtual SLE.Expression MakeExpression (BuilderContext ctx)
 945                 {
 946                         throw new NotImplementedException ("MakeExpression for " + GetType ());
 947                 }
 948         }
 949
 950         /// <summary>
 951         ///   This is just a base class for expressions that can
 952         ///   appear on statements (invocations, object creation,
 953         ///   assignments, post/pre increment and decrement).  The idea
 954         ///   being that they would support an extra Emition interface that
 955         ///   does not leave a result on the stack.
 956         /// </summary>
 957         public abstract class ExpressionStatement : Expression {
 958
 959                 public ExpressionStatement ResolveStatement (BlockContext ec)
 960                 {
 961                         Expression e = Resolve (ec);
 962                         if (e == null)
 963                                 return null;
 964
 965                         ExpressionStatement es = e as ExpressionStatement;
 966                         if (es == null)
 967                                 Error_InvalidExpressionStatement (ec);
 968
 969                         return es;
 970                 }
 971
 972                 /// <summary>
 973                 ///   Requests the expression to be emitted in a `statement'
 974                 ///   context.  This means that no new value is left on the
 975                 ///   stack after invoking this method (constrasted with
 976                 ///   Emit that will always leave a value on the stack).
 977                 /// </summary>
 978                 public abstract void EmitStatement (EmitContext ec);
 979
 980                 public override void EmitSideEffect (EmitContext ec)
 981                 {
 982                         EmitStatement (ec);
 983                 }
 984         }
 985
 986         /// <summary>
 987         ///   This kind of cast is used to encapsulate the child
 988         ///   whose type is child.Type into an expression that is
 989         ///   reported to return "return_type".  This is used to encapsulate
 990         ///   expressions which have compatible types, but need to be dealt
 991         ///   at higher levels with.
 992         ///
 993         ///   For example, a "byte" expression could be encapsulated in one
 994         ///   of these as an "unsigned int".  The type for the expression
 995         ///   would be "unsigned int".
 996         ///
 997         /// </summary>
 998         public abstract class TypeCast : Expression
 999         {
1000                 protected readonly Expression child;
1001
1002                 protected TypeCast (Expression child, TypeSpec return_type)
1003                 {
1004                         eclass = child.eclass;
1005                         loc = child.Location;
1006                         type = return_type;
1007                         this.child = child;
1008                 }
1009
1010                 public Expression Child {
1011                         get {
1012                                 return child;
1013                         }
1014                 }
1015
1016                 public override Expression CreateExpressionTree (ResolveContext ec)
1017                 {
1018                         Arguments args = new Arguments (2);
1019                         args.Add (new Argument (child.CreateExpressionTree (ec)));
1020                         args.Add (new Argument (new TypeOf (new TypeExpression (type, loc), loc)));
1021
1022                         if (type.IsPointer || child.Type.IsPointer)
1023                                 Error_PointerInsideExpressionTree (ec);
1024
1025                         return CreateExpressionFactoryCall (ec, ec.HasSet (ResolveContext.Options.CheckedScope) ? "ConvertChecked" : "Convert", args);
1026                 }
1027
1028                 protected override Expression DoResolve (ResolveContext ec)
1029                 {
1030                         // This should never be invoked, we are born in fully
1031                         // initialized state.
1032
1033                         return this;
1034                 }
1035
1036                 public override void Emit (EmitContext ec)
1037                 {
1038                         child.Emit (ec);
1039                 }
1040
1041                 public override SLE.Expression MakeExpression (BuilderContext ctx)
1042                 {
1043                         return ctx.HasSet (BuilderContext.Options.CheckedScope) ?
1044                                 SLE.Expression.ConvertChecked (child.MakeExpression (ctx), type.GetMetaInfo ()) :
1045                                 SLE.Expression.Convert (child.MakeExpression (ctx), type.GetMetaInfo ());
1046                 }
1047
1048                 protected override void CloneTo (CloneContext clonectx, Expression t)
1049                 {
1050                         // Nothing to clone
1051                 }
1052
1053                 public override bool IsNull {
1054                         get { return child.IsNull; }
1055                 }
1056         }
1057
1058         public class EmptyCast : TypeCast {
1059                 EmptyCast (Expression child, TypeSpec target_type)
1060                         : base (child, target_type)
1061                 {
1062                 }
1063
1064                 public static Expression Create (Expression child, TypeSpec type)
1065                 {
1066                         Constant c = child as Constant;
1067                         if (c != null)
1068                                 return new EmptyConstantCast (c, type);
1069
1070                         EmptyCast e = child as EmptyCast;
1071                         if (e != null)
1072                                 return new EmptyCast (e.child, type);
1073
1074                         return new EmptyCast (child, type);
1075                 }
1076
1077                 public override void EmitBranchable (EmitContext ec, Label label, bool on_true)
1078                 {
1079                         child.EmitBranchable (ec, label, on_true);
1080                 }
1081
1082                 public override void EmitSideEffect (EmitContext ec)
1083                 {
1084                         child.EmitSideEffect (ec);
1085                 }
1086         }
1087
1088         //
1089         // Used for predefined class library user casts (no obsolete check, etc.)
1090         //
1091         public class OperatorCast : TypeCast {
1092                 MethodSpec conversion_operator;
1093
1094                 public OperatorCast (Expression child, TypeSpec target_type)
1095                         : this (child, target_type, false)
1096                 {
1097                 }
1098
1099                 public OperatorCast (Expression child, TypeSpec target_type, bool find_explicit)
1100                         : base (child, target_type)
1101                 {
1102                         conversion_operator = GetConversionOperator (find_explicit);
1103                         if (conversion_operator == null)
1104                                 throw new InternalErrorException ("Outer conversion routine is out of sync");
1105                 }
1106
1107                 // Returns the implicit operator that converts from
1108                 // 'child.Type' to our target type (type)
1109                 MethodSpec GetConversionOperator (bool find_explicit)
1110                 {
1111                         var op = find_explicit ? Operator.OpType.Explicit : Operator.OpType.Implicit;
1112
1113                         var mi = MemberCache.GetUserOperator (child.Type, op, true);
1114                         if (mi == null){
1115                                 mi = MemberCache.GetUserOperator (type, op, true);
1116                         }
1117
1118                         foreach (MethodSpec oper in mi) {
1119                                 if (oper.ReturnType != type)
1120                                         continue;
1121
1122                                 if (oper.Parameters.Types [0] == child.Type)
1123                                         return oper;
1124                         }
1125
1126                         return null;
1127                 }
1128
1129                 public override void Emit (EmitContext ec)
1130                 {
1131                         child.Emit (ec);
1132                         ec.Emit (OpCodes.Call, conversion_operator);
1133                 }
1134         }
1135
1136         /// <summary>
1137         ///     This is a numeric cast to a Decimal
1138         /// </summary>
1139         public class CastToDecimal : OperatorCast {
1140                 public CastToDecimal (Expression child)
1141                         : this (child, false)
1142                 {
1143                 }
1144
1145                 public CastToDecimal (Expression child, bool find_explicit)
1146                         : base (child, TypeManager.decimal_type, find_explicit)
1147                 {
1148                 }
1149         }
1150
1151         /// <summary>
1152         ///     This is an explicit numeric cast from a Decimal
1153         /// </summary>
1154         public class CastFromDecimal : TypeCast
1155         {
1156                 static Dictionary<TypeSpec, MethodSpec> operators;
1157
1158                 public CastFromDecimal (Expression child, TypeSpec return_type)
1159                         : base (child, return_type)
1160                 {
1161                         if (child.Type != TypeManager.decimal_type)
1162                                 throw new ArgumentException ("Expected decimal child " + child.Type.GetSignatureForError ());
1163                 }
1164
1165                 // Returns the explicit operator that converts from an
1166                 // express of type System.Decimal to 'type'.
1167                 public Expression Resolve ()
1168                 {
1169                         if (operators == null) {
1170                                 var all_oper = MemberCache.GetUserOperator (TypeManager.decimal_type, Operator.OpType.Explicit, true);
1171
1172                                 operators = new Dictionary<TypeSpec, MethodSpec> ();
1173                                 foreach (MethodSpec oper in all_oper) {
1174                                         AParametersCollection pd = oper.Parameters;
1175                                         if (pd.Types [0] == TypeManager.decimal_type)
1176                                                 operators.Add (oper.ReturnType, oper);
1177                                 }
1178                         }
1179
1180                         return operators.ContainsKey (type) ? this : null;
1181                 }
1182
1183                 public override void Emit (EmitContext ec)
1184                 {
1185                         child.Emit (ec);
1186
1187                         ec.Emit (OpCodes.Call, operators [type]);
1188                 }
1189
1190                 public static void Reset ()
1191                 {
1192                         operators = null;
1193                 }
1194         }
1195
1196
1197         //
1198         // Constant specialization of EmptyCast.
1199         // We need to special case this since an empty cast of
1200         // a constant is still a constant.
1201         //
1202         public class EmptyConstantCast : Constant
1203         {
1204                 public Constant child;
1205
1206                 public EmptyConstantCast (Constant child, TypeSpec type)
1207                         : base (child.Location)
1208                 {
1209                         if (child == null)
1210                                 throw new ArgumentNullException ("child");
1211
1212                         this.child = child;
1213                         this.eclass = child.eclass;
1214                         this.type = type;
1215                 }
1216
1217                 public override string AsString ()
1218                 {
1219                         return child.AsString ();
1220                 }
1221
1222                 public override object GetValue ()
1223                 {
1224                         return child.GetValue ();
1225                 }
1226
1227                 public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
1228                 {
1229                         if (child.Type == target_type)
1230                                 return child;
1231
1232                         // FIXME: check that 'type' can be converted to 'target_type' first
1233                         return child.ConvertExplicitly (in_checked_context, target_type);
1234                 }
1235
1236                 public override Expression CreateExpressionTree (ResolveContext ec)
1237                 {
1238                         Arguments args = Arguments.CreateForExpressionTree (ec, null,
1239                                 child.CreateExpressionTree (ec),
1240                                 new TypeOf (new TypeExpression (type, loc), loc));
1241
1242                         if (type.IsPointer)
1243                                 Error_PointerInsideExpressionTree (ec);
1244
1245                         return CreateExpressionFactoryCall (ec, "Convert", args);
1246                 }
1247
1248                 public override bool IsDefaultValue {
1249                         get { return child.IsDefaultValue; }
1250                 }
1251
1252                 public override bool IsNegative {
1253                         get { return child.IsNegative; }
1254                 }
1255
1256                 public override bool IsNull {
1257                         get { return child.IsNull; }
1258                 }
1259
1260                 public override bool IsOneInteger {
1261                         get { return child.IsOneInteger; }
1262                 }
1263
1264                 public override bool IsZeroInteger {
1265                         get { return child.IsZeroInteger; }
1266                 }
1267
1268                 protected override Expression DoResolve (ResolveContext rc)
1269                 {
1270                         return this;
1271                 }
1272
1273                 public override void Emit (EmitContext ec)
1274                 {
1275                         child.Emit (ec);
1276                 }
1277
1278                 public override void EmitBranchable (EmitContext ec, Label label, bool on_true)
1279                 {
1280                         child.EmitBranchable (ec, label, on_true);
1281
1282                         // Only to make verifier happy
1283                         if (TypeManager.IsGenericParameter (type) && child.IsNull)
1284                                 ec.Emit (OpCodes.Unbox_Any, type);
1285                 }
1286
1287                 public override void EmitSideEffect (EmitContext ec)
1288                 {
1289                         child.EmitSideEffect (ec);
1290                 }
1291
1292                 public override Constant ConvertImplicitly (ResolveContext rc, TypeSpec target_type)
1293                 {
1294                         // FIXME: Do we need to check user conversions?
1295                         if (!Convert.ImplicitStandardConversionExists (this, target_type))
1296                                 return null;
1297                         return child.ConvertImplicitly (rc, target_type);
1298                 }
1299         }
1300
1301         /// <summary>
1302         ///  This class is used to wrap literals which belong inside Enums
1303         /// </summary>
1304         public class EnumConstant : Constant
1305         {
1306                 public Constant Child;
1307
1308                 public EnumConstant (Constant child, TypeSpec enum_type)
1309                         : base (child.Location)
1310                 {
1311                         this.Child = child;
1312                         this.type = enum_type;
1313                 }
1314
1315                 protected EnumConstant (Location loc)
1316                         : base (loc)
1317                 {
1318                 }
1319
1320                 protected override Expression DoResolve (ResolveContext rc)
1321                 {
1322                         Child = Child.Resolve (rc);
1323                         this.eclass = ExprClass.Value;
1324                         return this;
1325                 }
1326
1327                 public override void Emit (EmitContext ec)
1328                 {
1329                         Child.Emit (ec);
1330                 }
1331
1332                 public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
1333                 {
1334                         Child.EncodeAttributeValue (rc, enc, Child.Type);
1335                 }
1336
1337                 public override void EmitBranchable (EmitContext ec, Label label, bool on_true)
1338                 {
1339                         Child.EmitBranchable (ec, label, on_true);
1340                 }
1341
1342                 public override void EmitSideEffect (EmitContext ec)
1343                 {
1344                         Child.EmitSideEffect (ec);
1345                 }
1346
1347                 public override string GetSignatureForError()
1348                 {
1349                         return TypeManager.CSharpName (Type);
1350                 }
1351
1352                 public override object GetValue ()
1353                 {
1354                         return Child.GetValue ();
1355                 }
1356
1357                 public override object GetTypedValue ()
1358                 {
1359                         // FIXME: runtime is not ready to work with just emited enums
1360                         if (!RootContext.StdLib) {
1361                                 return Child.GetValue ();
1362                         }
1363
1364 #if MS_COMPATIBLE
1365                         // Small workaround for big problem
1366                         // System.Enum.ToObject cannot be called on dynamic types
1367                         // EnumBuilder has to be used, but we cannot use EnumBuilder
1368                         // because it does not properly support generics
1369                         //
1370                         // This works only sometimes
1371                         //
1372                         if (type.MemberDefinition is TypeContainer)
1373                                 return Child.GetValue ();
1374 #endif
1375
1376                         return System.Enum.ToObject (type.GetMetaInfo (), Child.GetValue ());
1377                 }
1378
1379                 public override string AsString ()
1380                 {
1381                         return Child.AsString ();
1382                 }
1383
1384                 public EnumConstant Increment()
1385                 {
1386                         return new EnumConstant (((IntegralConstant) Child).Increment (), type);
1387                 }
1388
1389                 public override bool IsDefaultValue {
1390                         get {
1391                                 return Child.IsDefaultValue;
1392                         }
1393                 }
1394
1395                 public override bool IsZeroInteger {
1396                         get { return Child.IsZeroInteger; }
1397                 }
1398
1399                 public override bool IsNegative {
1400                         get {
1401                                 return Child.IsNegative;
1402                         }
1403                 }
1404
1405                 public override Constant ConvertExplicitly(bool in_checked_context, TypeSpec target_type)
1406                 {
1407                         if (Child.Type == target_type)
1408                                 return Child;
1409
1410                         return Child.ConvertExplicitly (in_checked_context, target_type);
1411                 }
1412
1413                 public override Constant ConvertImplicitly (ResolveContext rc, TypeSpec type)
1414                 {
1415                         if (this.type == type) {
1416                                 return this;
1417                         }
1418
1419                         if (!Convert.ImplicitStandardConversionExists (this, type)){
1420                                 return null;
1421                         }
1422
1423                         return Child.ConvertImplicitly (rc, type);
1424                 }
1425         }
1426
1427         /// <summary>
1428         ///   This kind of cast is used to encapsulate Value Types in objects.
1429         ///
1430         ///   The effect of it is to box the value type emitted by the previous
1431         ///   operation.
1432         /// </summary>
1433         public class BoxedCast : TypeCast {
1434
1435                 public BoxedCast (Expression expr, TypeSpec target_type)
1436                         : base (expr, target_type)
1437                 {
1438                         eclass = ExprClass.Value;
1439                 }
1440
1441                 protected override Expression DoResolve (ResolveContext ec)
1442                 {
1443                         // This should never be invoked, we are born in fully
1444                         // initialized state.
1445
1446                         return this;
1447                 }
1448
1449                 public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
1450                 {
1451                         enc.Encode (child.Type);
1452                         child.EncodeAttributeValue (rc, enc, child.Type);
1453                 }
1454
1455                 public override void Emit (EmitContext ec)
1456                 {
1457                         base.Emit (ec);
1458
1459                         ec.Emit (OpCodes.Box, child.Type);
1460                 }
1461
1462                 public override void EmitSideEffect (EmitContext ec)
1463                 {
1464                         // boxing is side-effectful, since it involves runtime checks, except when boxing to Object or ValueType
1465                         // so, we need to emit the box+pop instructions in most cases
1466                         if (TypeManager.IsStruct (child.Type) &&
1467                             (type == TypeManager.object_type || type == TypeManager.value_type))
1468                                 child.EmitSideEffect (ec);
1469                         else
1470                                 base.EmitSideEffect (ec);
1471                 }
1472         }
1473
1474         public class UnboxCast : TypeCast {
1475                 public UnboxCast (Expression expr, TypeSpec return_type)
1476                         : base (expr, return_type)
1477                 {
1478                 }
1479
1480                 protected override Expression DoResolve (ResolveContext ec)
1481                 {
1482                         // This should never be invoked, we are born in fully
1483                         // initialized state.
1484
1485                         return this;
1486                 }
1487
1488                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
1489                 {
1490                         if (right_side == EmptyExpression.LValueMemberAccess || right_side == EmptyExpression.LValueMemberOutAccess)
1491                                 ec.Report.Error (445, loc, "Cannot modify the result of an unboxing conversion");
1492                         return base.DoResolveLValue (ec, right_side);
1493                 }
1494
1495                 public override void Emit (EmitContext ec)
1496                 {
1497                         base.Emit (ec);
1498
1499                         ec.Emit (OpCodes.Unbox_Any, type);
1500                 }
1501         }
1502
1503         /// <summary>
1504         ///   This is used to perform explicit numeric conversions.
1505         ///
1506         ///   Explicit numeric conversions might trigger exceptions in a checked
1507         ///   context, so they should generate the conv.ovf opcodes instead of
1508         ///   conv opcodes.
1509         /// </summary>
1510         public class ConvCast : TypeCast {
1511                 public enum Mode : byte {
1512                         I1_U1, I1_U2, I1_U4, I1_U8, I1_CH,
1513                         U1_I1, U1_CH,
1514                         I2_I1, I2_U1, I2_U2, I2_U4, I2_U8, I2_CH,
1515                         U2_I1, U2_U1, U2_I2, U2_CH,
1516                         I4_I1, I4_U1, I4_I2, I4_U2, I4_U4, I4_U8, I4_CH,
1517                         U4_I1, U4_U1, U4_I2, U4_U2, U4_I4, U4_CH,
1518                         I8_I1, I8_U1, I8_I2, I8_U2, I8_I4, I8_U4, I8_U8, I8_CH, I8_I,
1519                         U8_I1, U8_U1, U8_I2, U8_U2, U8_I4, U8_U4, U8_I8, U8_CH, U8_I,
1520                         CH_I1, CH_U1, CH_I2,
1521                         R4_I1, R4_U1, R4_I2, R4_U2, R4_I4, R4_U4, R4_I8, R4_U8, R4_CH,
1522                         R8_I1, R8_U1, R8_I2, R8_U2, R8_I4, R8_U4, R8_I8, R8_U8, R8_CH, R8_R4,
1523                         I_I8,
1524                 }
1525
1526                 Mode mode;
1527
1528                 public ConvCast (Expression child, TypeSpec return_type, Mode m)
1529                         : base (child, return_type)
1530                 {
1531                         mode = m;
1532                 }
1533
1534                 protected override Expression DoResolve (ResolveContext ec)
1535                 {
1536                         // This should never be invoked, we are born in fully
1537                         // initialized state.
1538
1539                         return this;
1540                 }
1541
1542                 public override string ToString ()
1543                 {
1544                         return String.Format ("ConvCast ({0}, {1})", mode, child);
1545                 }
1546
1547                 public override void Emit (EmitContext ec)
1548                 {
1549                         base.Emit (ec);
1550
1551                         if (ec.HasSet (EmitContext.Options.CheckedScope)) {
1552                                 switch (mode){
1553                                 case Mode.I1_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1554                                 case Mode.I1_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1555                                 case Mode.I1_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1556                                 case Mode.I1_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1557                                 case Mode.I1_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1558
1559                                 case Mode.U1_I1: ec.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1560                                 case Mode.U1_CH: /* nothing */ break;
1561
1562                                 case Mode.I2_I1: ec.Emit (OpCodes.Conv_Ovf_I1); break;
1563                                 case Mode.I2_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1564                                 case Mode.I2_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1565                                 case Mode.I2_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1566                                 case Mode.I2_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1567                                 case Mode.I2_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1568
1569                                 case Mode.U2_I1: ec.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1570                                 case Mode.U2_U1: ec.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1571                                 case Mode.U2_I2: ec.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1572                                 case Mode.U2_CH: /* nothing */ break;
1573
1574                                 case Mode.I4_I1: ec.Emit (OpCodes.Conv_Ovf_I1); break;
1575                                 case Mode.I4_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1576                                 case Mode.I4_I2: ec.Emit (OpCodes.Conv_Ovf_I2); break;
1577                                 case Mode.I4_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1578                                 case Mode.I4_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1579                                 case Mode.I4_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1580                                 case Mode.I4_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1581
1582                                 case Mode.U4_I1: ec.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1583                                 case Mode.U4_U1: ec.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1584                                 case Mode.U4_I2: ec.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1585                                 case Mode.U4_U2: ec.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1586                                 case Mode.U4_I4: ec.Emit (OpCodes.Conv_Ovf_I4_Un); break;
1587                                 case Mode.U4_CH: ec.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1588
1589                                 case Mode.I8_I1: ec.Emit (OpCodes.Conv_Ovf_I1); break;
1590                                 case Mode.I8_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1591                                 case Mode.I8_I2: ec.Emit (OpCodes.Conv_Ovf_I2); break;
1592                                 case Mode.I8_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1593                                 case Mode.I8_I4: ec.Emit (OpCodes.Conv_Ovf_I4); break;
1594                                 case Mode.I8_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1595                                 case Mode.I8_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1596                                 case Mode.I8_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1597                                 case Mode.I8_I: ec.Emit (OpCodes.Conv_Ovf_U); break;
1598
1599                                 case Mode.U8_I1: ec.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1600                                 case Mode.U8_U1: ec.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1601                                 case Mode.U8_I2: ec.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1602                                 case Mode.U8_U2: ec.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1603                                 case Mode.U8_I4: ec.Emit (OpCodes.Conv_Ovf_I4_Un); break;
1604                                 case Mode.U8_U4: ec.Emit (OpCodes.Conv_Ovf_U4_Un); break;
1605                                 case Mode.U8_I8: ec.Emit (OpCodes.Conv_Ovf_I8_Un); break;
1606                                 case Mode.U8_CH: ec.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1607                                 case Mode.U8_I: ec.Emit (OpCodes.Conv_Ovf_U_Un); break;
1608
1609                                 case Mode.CH_I1: ec.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1610                                 case Mode.CH_U1: ec.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1611                                 case Mode.CH_I2: ec.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1612
1613                                 case Mode.R4_I1: ec.Emit (OpCodes.Conv_Ovf_I1); break;
1614                                 case Mode.R4_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1615                                 case Mode.R4_I2: ec.Emit (OpCodes.Conv_Ovf_I2); break;
1616                                 case Mode.R4_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1617                                 case Mode.R4_I4: ec.Emit (OpCodes.Conv_Ovf_I4); break;
1618                                 case Mode.R4_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1619                                 case Mode.R4_I8: ec.Emit (OpCodes.Conv_Ovf_I8); break;
1620                                 case Mode.R4_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1621                                 case Mode.R4_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1622
1623                                 case Mode.R8_I1: ec.Emit (OpCodes.Conv_Ovf_I1); break;
1624                                 case Mode.R8_U1: ec.Emit (OpCodes.Conv_Ovf_U1); break;
1625                                 case Mode.R8_I2: ec.Emit (OpCodes.Conv_Ovf_I2); break;
1626                                 case Mode.R8_U2: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1627                                 case Mode.R8_I4: ec.Emit (OpCodes.Conv_Ovf_I4); break;
1628                                 case Mode.R8_U4: ec.Emit (OpCodes.Conv_Ovf_U4); break;
1629                                 case Mode.R8_I8: ec.Emit (OpCodes.Conv_Ovf_I8); break;
1630                                 case Mode.R8_U8: ec.Emit (OpCodes.Conv_Ovf_U8); break;
1631                                 case Mode.R8_CH: ec.Emit (OpCodes.Conv_Ovf_U2); break;
1632                                 case Mode.R8_R4: ec.Emit (OpCodes.Conv_R4); break;
1633
1634                                 case Mode.I_I8: ec.Emit (OpCodes.Conv_Ovf_I8_Un); break;
1635                                 }
1636                         } else {
1637                                 switch (mode){
1638                                 case Mode.I1_U1: ec.Emit (OpCodes.Conv_U1); break;
1639                                 case Mode.I1_U2: ec.Emit (OpCodes.Conv_U2); break;
1640                                 case Mode.I1_U4: ec.Emit (OpCodes.Conv_U4); break;
1641                                 case Mode.I1_U8: ec.Emit (OpCodes.Conv_I8); break;
1642                                 case Mode.I1_CH: ec.Emit (OpCodes.Conv_U2); break;
1643
1644                                 case Mode.U1_I1: ec.Emit (OpCodes.Conv_I1); break;
1645                                 case Mode.U1_CH: ec.Emit (OpCodes.Conv_U2); break;
1646
1647                                 case Mode.I2_I1: ec.Emit (OpCodes.Conv_I1); break;
1648                                 case Mode.I2_U1: ec.Emit (OpCodes.Conv_U1); break;
1649                                 case Mode.I2_U2: ec.Emit (OpCodes.Conv_U2); break;
1650                                 case Mode.I2_U4: ec.Emit (OpCodes.Conv_U4); break;
1651                                 case Mode.I2_U8: ec.Emit (OpCodes.Conv_I8); break;
1652                                 case Mode.I2_CH: ec.Emit (OpCodes.Conv_U2); break;
1653
1654                                 case Mode.U2_I1: ec.Emit (OpCodes.Conv_I1); break;
1655                                 case Mode.U2_U1: ec.Emit (OpCodes.Conv_U1); break;
1656                                 case Mode.U2_I2: ec.Emit (OpCodes.Conv_I2); break;
1657                                 case Mode.U2_CH: /* nothing */ break;
1658
1659                                 case Mode.I4_I1: ec.Emit (OpCodes.Conv_I1); break;
1660                                 case Mode.I4_U1: ec.Emit (OpCodes.Conv_U1); break;
1661                                 case Mode.I4_I2: ec.Emit (OpCodes.Conv_I2); break;
1662                                 case Mode.I4_U4: /* nothing */ break;
1663                                 case Mode.I4_U2: ec.Emit (OpCodes.Conv_U2); break;
1664                                 case Mode.I4_U8: ec.Emit (OpCodes.Conv_I8); break;
1665                                 case Mode.I4_CH: ec.Emit (OpCodes.Conv_U2); break;
1666
1667                                 case Mode.U4_I1: ec.Emit (OpCodes.Conv_I1); break;
1668                                 case Mode.U4_U1: ec.Emit (OpCodes.Conv_U1); break;
1669                                 case Mode.U4_I2: ec.Emit (OpCodes.Conv_I2); break;
1670                                 case Mode.U4_U2: ec.Emit (OpCodes.Conv_U2); break;
1671                                 case Mode.U4_I4: /* nothing */ break;
1672                                 case Mode.U4_CH: ec.Emit (OpCodes.Conv_U2); break;
1673
1674                                 case Mode.I8_I1: ec.Emit (OpCodes.Conv_I1); break;
1675                                 case Mode.I8_U1: ec.Emit (OpCodes.Conv_U1); break;
1676                                 case Mode.I8_I2: ec.Emit (OpCodes.Conv_I2); break;
1677                                 case Mode.I8_U2: ec.Emit (OpCodes.Conv_U2); break;
1678                                 case Mode.I8_I4: ec.Emit (OpCodes.Conv_I4); break;
1679                                 case Mode.I8_U4: ec.Emit (OpCodes.Conv_U4); break;
1680                                 case Mode.I8_U8: /* nothing */ break;
1681                                 case Mode.I8_CH: ec.Emit (OpCodes.Conv_U2); break;
1682                                 case Mode.I8_I: ec.Emit (OpCodes.Conv_U); break;
1683
1684                                 case Mode.U8_I1: ec.Emit (OpCodes.Conv_I1); break;
1685                                 case Mode.U8_U1: ec.Emit (OpCodes.Conv_U1); break;
1686                                 case Mode.U8_I2: ec.Emit (OpCodes.Conv_I2); break;
1687                                 case Mode.U8_U2: ec.Emit (OpCodes.Conv_U2); break;
1688                                 case Mode.U8_I4: ec.Emit (OpCodes.Conv_I4); break;
1689                                 case Mode.U8_U4: ec.Emit (OpCodes.Conv_U4); break;
1690                                 case Mode.U8_I8: /* nothing */ break;
1691                                 case Mode.U8_CH: ec.Emit (OpCodes.Conv_U2); break;
1692                                 case Mode.U8_I: ec.Emit (OpCodes.Conv_U); break;
1693
1694                                 case Mode.CH_I1: ec.Emit (OpCodes.Conv_I1); break;
1695                                 case Mode.CH_U1: ec.Emit (OpCodes.Conv_U1); break;
1696                                 case Mode.CH_I2: ec.Emit (OpCodes.Conv_I2); break;
1697
1698                                 case Mode.R4_I1: ec.Emit (OpCodes.Conv_I1); break;
1699                                 case Mode.R4_U1: ec.Emit (OpCodes.Conv_U1); break;
1700                                 case Mode.R4_I2: ec.Emit (OpCodes.Conv_I2); break;
1701                                 case Mode.R4_U2: ec.Emit (OpCodes.Conv_U2); break;
1702                                 case Mode.R4_I4: ec.Emit (OpCodes.Conv_I4); break;
1703                                 case Mode.R4_U4: ec.Emit (OpCodes.Conv_U4); break;
1704                                 case Mode.R4_I8: ec.Emit (OpCodes.Conv_I8); break;
1705                                 case Mode.R4_U8: ec.Emit (OpCodes.Conv_U8); break;
1706                                 case Mode.R4_CH: ec.Emit (OpCodes.Conv_U2); break;
1707
1708                                 case Mode.R8_I1: ec.Emit (OpCodes.Conv_I1); break;
1709                                 case Mode.R8_U1: ec.Emit (OpCodes.Conv_U1); break;
1710                                 case Mode.R8_I2: ec.Emit (OpCodes.Conv_I2); break;
1711                                 case Mode.R8_U2: ec.Emit (OpCodes.Conv_U2); break;
1712                                 case Mode.R8_I4: ec.Emit (OpCodes.Conv_I4); break;
1713                                 case Mode.R8_U4: ec.Emit (OpCodes.Conv_U4); break;
1714                                 case Mode.R8_I8: ec.Emit (OpCodes.Conv_I8); break;
1715                                 case Mode.R8_U8: ec.Emit (OpCodes.Conv_U8); break;
1716                                 case Mode.R8_CH: ec.Emit (OpCodes.Conv_U2); break;
1717                                 case Mode.R8_R4: ec.Emit (OpCodes.Conv_R4); break;
1718
1719                                 case Mode.I_I8: ec.Emit (OpCodes.Conv_U8); break;
1720                                 }
1721                         }
1722                 }
1723         }
1724
1725         public class OpcodeCast : TypeCast {
1726                 readonly OpCode op;
1727
1728                 public OpcodeCast (Expression child, TypeSpec return_type, OpCode op)
1729                         : base (child, return_type)
1730                 {
1731                         this.op = op;
1732                 }
1733
1734                 protected override Expression DoResolve (ResolveContext ec)
1735                 {
1736                         // This should never be invoked, we are born in fully
1737                         // initialized state.
1738
1739                         return this;
1740                 }
1741
1742                 public override void Emit (EmitContext ec)
1743                 {
1744                         base.Emit (ec);
1745                         ec.Emit (op);
1746                 }
1747
1748                 public TypeSpec UnderlyingType {
1749                         get { return child.Type; }
1750                 }
1751         }
1752
1753         /// <summary>
1754         ///   This kind of cast is used to encapsulate a child and cast it
1755         ///   to the class requested
1756         /// </summary>
1757         public sealed class ClassCast : TypeCast {
1758                 readonly bool forced;
1759
1760                 public ClassCast (Expression child, TypeSpec return_type)
1761                         : base (child, return_type)
1762                 {
1763                 }
1764
1765                 public ClassCast (Expression child, TypeSpec return_type, bool forced)
1766                         : base (child, return_type)
1767                 {
1768                         this.forced = forced;
1769                 }
1770
1771                 public override void Emit (EmitContext ec)
1772                 {
1773                         base.Emit (ec);
1774
1775                         bool gen = TypeManager.IsGenericParameter (child.Type);
1776                         if (gen)
1777                                 ec.Emit (OpCodes.Box, child.Type);
1778
1779                         if (type.IsGenericParameter) {
1780                                 ec.Emit (OpCodes.Unbox_Any, type);
1781                                 return;
1782                         }
1783
1784                         if (gen && !forced)
1785                                 return;
1786
1787                         ec.Emit (OpCodes.Castclass, type);
1788                 }
1789         }
1790
1791         //
1792         // Created during resolving pahse when an expression is wrapped or constantified
1793         // and original expression can be used later (e.g. for expression trees)
1794         //
1795         public class ReducedExpression : Expression
1796         {
1797                 sealed class ReducedConstantExpression : EmptyConstantCast
1798                 {
1799                         readonly Expression orig_expr;
1800
1801                         public ReducedConstantExpression (Constant expr, Expression orig_expr)
1802                                 : base (expr, expr.Type)
1803                         {
1804                                 this.orig_expr = orig_expr;
1805                         }
1806
1807                         public override Constant ConvertImplicitly (ResolveContext rc, TypeSpec target_type)
1808                         {
1809                                 Constant c = base.ConvertImplicitly (rc, target_type);
1810                                 if (c != null)
1811                                         c = new ReducedConstantExpression (c, orig_expr);
1812
1813                                 return c;
1814                         }
1815
1816                         public override Expression CreateExpressionTree (ResolveContext ec)
1817                         {
1818                                 return orig_expr.CreateExpressionTree (ec);
1819                         }
1820
1821                         public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
1822                         {
1823                                 Constant c = base.ConvertExplicitly (in_checked_context, target_type);
1824                                 if (c != null)
1825                                         c = new ReducedConstantExpression (c, orig_expr);
1826                                 return c;
1827                         }
1828                 }
1829
1830                 sealed class ReducedExpressionStatement : ExpressionStatement
1831                 {
1832                         readonly Expression orig_expr;
1833                         readonly ExpressionStatement stm;
1834
1835                         public ReducedExpressionStatement (ExpressionStatement stm, Expression orig)
1836                         {
1837                                 this.orig_expr = orig;
1838                                 this.stm = stm;
1839                                 this.loc = orig.Location;
1840                         }
1841
1842                         public override Expression CreateExpressionTree (ResolveContext ec)
1843                         {
1844                                 return orig_expr.CreateExpressionTree (ec);
1845                         }
1846
1847                         protected override Expression DoResolve (ResolveContext ec)
1848                         {
1849                                 eclass = stm.eclass;
1850                                 type = stm.Type;
1851                                 return this;
1852                         }
1853
1854                         public override void Emit (EmitContext ec)
1855                         {
1856                                 stm.Emit (ec);
1857                         }
1858
1859                         public override void EmitStatement (EmitContext ec)
1860                         {
1861                                 stm.EmitStatement (ec);
1862                         }
1863                 }
1864
1865                 readonly Expression expr, orig_expr;
1866
1867                 private ReducedExpression (Expression expr, Expression orig_expr)
1868                 {
1869                         this.expr = expr;
1870                         this.eclass = expr.eclass;
1871                         this.type = expr.Type;
1872                         this.orig_expr = orig_expr;
1873                         this.loc = orig_expr.Location;
1874                 }
1875
1876                 //
1877                 // Creates fully resolved expression switcher
1878                 //
1879                 public static Constant Create (Constant expr, Expression original_expr)
1880                 {
1881                         if (expr.eclass == ExprClass.Unresolved)
1882                                 throw new ArgumentException ("Unresolved expression");
1883
1884                         return new ReducedConstantExpression (expr, original_expr);
1885                 }
1886
1887                 public static ExpressionStatement Create (ExpressionStatement s, Expression orig)
1888                 {
1889                         return new ReducedExpressionStatement (s, orig);
1890                 }
1891
1892                 //
1893                 // Creates unresolved reduce expression. The original expression has to be
1894                 // already resolved
1895                 //
1896                 public static Expression Create (Expression expr, Expression original_expr)
1897                 {
1898                         Constant c = expr as Constant;
1899                         if (c != null)
1900                                 return Create (c, original_expr);
1901
1902                         ExpressionStatement s = expr as ExpressionStatement;
1903                         if (s != null)
1904                                 return Create (s, original_expr);
1905
1906                         if (expr.eclass == ExprClass.Unresolved)
1907                                 throw new ArgumentException ("Unresolved expression");
1908
1909                         return new ReducedExpression (expr, original_expr);
1910                 }
1911
1912                 public override Expression CreateExpressionTree (ResolveContext ec)
1913                 {
1914                         return orig_expr.CreateExpressionTree (ec);
1915                 }
1916
1917                 protected override Expression DoResolve (ResolveContext ec)
1918                 {
1919                         return this;
1920                 }
1921
1922                 public override void Emit (EmitContext ec)
1923                 {
1924                         expr.Emit (ec);
1925                 }
1926
1927                 public override void EmitBranchable (EmitContext ec, Label target, bool on_true)
1928                 {
1929                         expr.EmitBranchable (ec, target, on_true);
1930                 }
1931
1932                 public override SLE.Expression MakeExpression (BuilderContext ctx)
1933                 {
1934                         return orig_expr.MakeExpression (ctx);
1935                 }
1936         }
1937
1938         //
1939         // Standard composite pattern
1940         //
1941         public abstract class CompositeExpression : Expression
1942         {
1943                 Expression expr;
1944
1945                 protected CompositeExpression (Expression expr)
1946                 {
1947                         this.expr = expr;
1948                         this.loc = expr.Location;
1949                 }
1950
1951                 public override Expression CreateExpressionTree (ResolveContext ec)
1952                 {
1953                         return expr.CreateExpressionTree (ec);
1954                 }
1955
1956                 public Expression Child {
1957                         get { return expr; }
1958                 }
1959
1960                 protected override Expression DoResolve (ResolveContext ec)
1961                 {
1962                         expr = expr.Resolve (ec);
1963                         if (expr != null) {
1964                                 type = expr.Type;
1965                                 eclass = expr.eclass;
1966                         }
1967
1968                         return this;
1969                 }
1970
1971                 public override void Emit (EmitContext ec)
1972                 {
1973                         expr.Emit (ec);
1974                 }
1975
1976                 public override bool IsNull {
1977                         get { return expr.IsNull; }
1978                 }
1979         }
1980
1981         //
1982         // Base of expressions used only to narrow resolve flow
1983         //
1984         public abstract class ShimExpression : Expression
1985         {
1986                 protected Expression expr;
1987
1988                 protected ShimExpression (Expression expr)
1989                 {
1990                         this.expr = expr;
1991                 }
1992
1993                 protected override void CloneTo (CloneContext clonectx, Expression t)
1994                 {
1995                         if (expr == null)
1996                                 return;
1997
1998                         ShimExpression target = (ShimExpression) t;
1999                         target.expr = expr.Clone (clonectx);
2000                 }
2001
2002                 public override Expression CreateExpressionTree (ResolveContext ec)
2003                 {
2004                         throw new NotSupportedException ("ET");
2005                 }
2006
2007                 public override void Emit (EmitContext ec)
2008                 {
2009                         throw new InternalErrorException ("Missing Resolve call");
2010                 }
2011
2012                 public Expression Expr {
2013                         get { return expr; }
2014                 }
2015         }
2016
2017         //
2018         // Unresolved type name expressions
2019         //
2020         public abstract class ATypeNameExpression : FullNamedExpression
2021         {
2022                 string name;
2023                 protected TypeArguments targs;
2024
2025                 protected ATypeNameExpression (string name, Location l)
2026                 {
2027                         this.name = name;
2028                         loc = l;
2029                 }
2030
2031                 protected ATypeNameExpression (string name, TypeArguments targs, Location l)
2032                 {
2033                         this.name = name;
2034                         this.targs = targs;
2035                         loc = l;
2036                 }
2037
2038                 protected ATypeNameExpression (string name, int arity, Location l)
2039                         : this (name, new UnboundTypeArguments (arity), l)
2040                 {
2041                 }
2042
2043                 #region Properties
2044
2045                 protected int Arity {
2046                         get {
2047                                 return targs == null ? 0 : targs.Count;
2048                         }
2049                 }
2050
2051                 public bool HasTypeArguments {
2052                         get {
2053                                 return targs != null && !targs.IsEmpty;
2054                         }
2055                 }
2056
2057                 public string Name {
2058                         get {
2059                                 return name;
2060                         }
2061                         set {
2062                                 name = value;
2063                         }
2064                 }
2065
2066                 public TypeArguments TypeArguments {
2067                         get {
2068                                 return targs;
2069                         }
2070                 }
2071
2072                 #endregion
2073
2074                 public override bool Equals (object obj)
2075                 {
2076                         ATypeNameExpression atne = obj as ATypeNameExpression;
2077                         return atne != null && atne.Name == Name &&
2078                                 (targs == null || targs.Equals (atne.targs));
2079                 }
2080
2081                 public override int GetHashCode ()
2082                 {
2083                         return Name.GetHashCode ();
2084                 }
2085
2086                 // TODO: Move it to MemberCore
2087                 public static string GetMemberType (MemberCore mc)
2088                 {
2089                         if (mc is Property)
2090                                 return "property";
2091                         if (mc is Indexer)
2092                                 return "indexer";
2093                         if (mc is FieldBase)
2094                                 return "field";
2095                         if (mc is MethodCore)
2096                                 return "method";
2097                         if (mc is EnumMember)
2098                                 return "enum";
2099                         if (mc is Event)
2100                                 return "event";
2101
2102                         return "type";
2103                 }
2104
2105                 public override string GetSignatureForError ()
2106                 {
2107                         if (targs != null) {
2108                                 return Name + "<" + targs.GetSignatureForError () + ">";
2109                         }
2110
2111                         return Name;
2112                 }
2113
2114                 public abstract Expression LookupNameExpression (ResolveContext rc, bool readMode, bool invocableOnly);
2115         }
2116
2117         /// <summary>
2118         ///   SimpleName expressions are formed of a single word and only happen at the beginning
2119         ///   of a dotted-name.
2120         /// </summary>
2121         public class SimpleName : ATypeNameExpression
2122         {
2123                 public SimpleName (string name, Location l)
2124                         : base (name, l)
2125                 {
2126                 }
2127
2128                 public SimpleName (string name, TypeArguments args, Location l)
2129                         : base (name, args, l)
2130                 {
2131                 }
2132
2133                 public SimpleName (string name, int arity, Location l)
2134                         : base (name, arity, l)
2135                 {
2136                 }
2137
2138                 public SimpleName GetMethodGroup ()
2139                 {
2140                         return new SimpleName (Name, targs, loc);
2141                 }
2142
2143                 protected virtual void Error_TypeOrNamespaceNotFound (IMemberContext ec)
2144                 {
2145                         if (ec.CurrentType != null) {
2146                                 if (ec.CurrentMemberDefinition != null) {
2147                                         MemberCore mc = ec.CurrentMemberDefinition.Parent.GetDefinition (Name);
2148                                         if (mc != null) {
2149                                                 Error_UnexpectedKind (ec.Compiler.Report, mc, "type", GetMemberType (mc), loc);
2150                                                 return;
2151                                         }
2152                                 }
2153
2154                                 /*
2155                                                                 // TODO MemberCache: Implement
2156
2157                                                                 string ns = ec.CurrentType.Namespace;
2158                                                                 string fullname = (ns.Length > 0) ? ns + "." + Name : Name;
2159                                                                 foreach (Assembly a in GlobalRootNamespace.Instance.Assemblies) {
2160                                                                         var type = a.GetType (fullname);
2161                                                                         if (type != null) {
2162                                                                                 ec.Compiler.Report.SymbolRelatedToPreviousError (type);
2163                                                                                 Expression.ErrorIsInaccesible (loc, TypeManager.CSharpName (type), ec.Compiler.Report);
2164                                                                                 return;
2165                                                                         }
2166                                                                 }
2167
2168                                                                 if (ec.CurrentTypeDefinition != null) {
2169                                                                         TypeSpec t = ec.CurrentTypeDefinition.LookupAnyGeneric (Name);
2170                                                                         if (t != null) {
2171                                                                                 Namespace.Error_InvalidNumberOfTypeArguments (ec.Compiler.Report, t, loc);
2172                                                                                 return;
2173                                                                         }
2174                                                                 }
2175                                 */
2176                         }
2177
2178                         FullNamedExpression retval = ec.LookupNamespaceOrType (Name, -System.Math.Max (1, Arity), loc, true);
2179                         if (retval != null) {
2180                                 Error_TypeArgumentsCannotBeUsed (ec.Compiler.Report, loc, retval.Type, Arity);
2181 /*
2182                                 var te = retval as TypeExpr;
2183                                 if (HasTypeArguments && te != null && !te.Type.IsGeneric)
2184                                         retval.Error_TypeArgumentsCannotBeUsed (ec.Compiler.Report, loc);
2185                                 else
2186                                         Namespace.Error_InvalidNumberOfTypeArguments (ec.Compiler.Report, retval.Type, loc);
2187 */
2188                                 return;
2189                         }
2190
2191                         NamespaceEntry.Error_NamespaceNotFound (loc, Name, ec.Compiler.Report);
2192                 }
2193
2194                 protected override Expression DoResolve (ResolveContext ec)
2195                 {
2196                         return SimpleNameResolve (ec, null, false);
2197                 }
2198
2199                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
2200                 {
2201                         return SimpleNameResolve (ec, right_side, false);
2202                 }
2203
2204                 public override FullNamedExpression ResolveAsTypeStep (IMemberContext ec, bool silent)
2205                 {
2206                         int errors = ec.Compiler.Report.Errors;
2207                         FullNamedExpression fne = ec.LookupNamespaceOrType (Name, Arity, loc, /*ignore_cs0104=*/ false);
2208
2209                         if (fne != null) {
2210                                 if (fne.Type != null && Arity > 0) {
2211                                         if (HasTypeArguments) {
2212                                                 GenericTypeExpr ct = new GenericTypeExpr (fne.Type, targs, loc);
2213                                                 return ct.ResolveAsTypeStep (ec, false);
2214                                         }
2215
2216                                         return new GenericOpenTypeExpr (fne.Type, loc);
2217                                 }
2218
2219                                 //
2220                                 // dynamic namespace is ignored when dynamic is allowed (does not apply to types)
2221                                 //
2222                                 if (!(fne is Namespace))
2223                                         return fne;
2224                         }
2225
2226                         if (Arity == 0 && Name == "dynamic" && RootContext.Version > LanguageVersion.V_3) {
2227                                 if (!PredefinedAttributes.Get.Dynamic.IsDefined) {
2228                                         ec.Compiler.Report.Error (1980, Location,
2229                                                 "Dynamic keyword requires `{0}' to be defined. Are you missing System.Core.dll assembly reference?",
2230                                                 PredefinedAttributes.Get.Dynamic.GetSignatureForError ());
2231                                 }
2232
2233                                 return new DynamicTypeExpr (loc);
2234                         }
2235
2236                         if (fne != null)
2237                                 return fne;
2238
2239                         if (silent || errors != ec.Compiler.Report.Errors)
2240                                 return null;
2241
2242                         Error_TypeOrNamespaceNotFound (ec);
2243                         return null;
2244                 }
2245
2246                 public override Expression LookupNameExpression (ResolveContext rc, bool readMode, bool invocableOnly)
2247                 {
2248                         int lookup_arity = Arity;
2249                         bool errorMode = false;
2250                         Expression e;
2251                         Block current_block = rc.CurrentBlock;
2252
2253                         while (true) {
2254                                 //
2255                                 // Stage 1: binding to local variables or parameters
2256                                 //
2257                                 if (current_block != null && lookup_arity == 0) {
2258                                         LocalInfo vi = current_block.GetLocalInfo (Name);
2259                                         if (vi != null) {
2260                                                 // TODO: pass vi in to speed things up
2261                                                 e = new LocalVariableReference (rc.CurrentBlock, Name, loc);
2262                                         } else {
2263                                                 e = current_block.Toplevel.GetParameterReference (Name, loc);
2264                                         }
2265
2266                                         if (e != null) {
2267                                                 if (Arity > 0)
2268                                                         Error_TypeArgumentsCannotBeUsed (rc.Report, "variable", Name, loc);
2269
2270                                                 return e;
2271                                         }
2272
2273                                         if (!errorMode)
2274                                                 current_block.CheckInvariantMeaningInBlock (Name, this, loc);
2275
2276 /*
2277                                         //if (errorMode) {
2278                                                 IKnownVariable ikv = current_block.Explicit.GetKnownVariable (Name);
2279                                                 if (ikv != null) {
2280                                                         LocalInfo li = ikv as LocalInfo;
2281                                                         // Supress CS0219 warning
2282                                                         if (li != null)
2283                                                                 li.Used = true;
2284
2285                                                         Error_VariableIsUsedBeforeItIsDeclared (rc.Report, Name);
2286                                                         return null;
2287                                                 }
2288                                         //}
2289 */
2290                                 }
2291
2292                                 //
2293                                 // Stage 2: Lookup members if we are inside a type up to top level type for nested types
2294                                 //
2295                                 TypeSpec member_type = rc.CurrentType;
2296                                 TypeSpec current_type = member_type;
2297                                 for (; member_type != null; member_type = member_type.DeclaringType) {
2298                                         var me = MemberLookup (errorMode ? null : rc, current_type, member_type, Name, lookup_arity, invocableOnly, loc) as MemberExpr;
2299                                         if (me == null)
2300                                                 continue;
2301
2302                                         if (errorMode) {
2303                                                 if (me is MethodGroupExpr) {
2304                                                         // Leave it to overload resolution to report correct error
2305                                                 } else {
2306                                                         // TODO: rc.Report.SymbolRelatedToPreviousError ()
2307                                                         ErrorIsInaccesible (rc, me.GetSignatureForError (), loc);
2308                                                 }
2309                                         } else {
2310                                                 //
2311                                                 // MemberLookup does not check accessors availability, this is actually needed for properties only
2312                                                 //
2313                                                 var pe = me as PropertyExpr;
2314                                                 if (pe != null) {
2315
2316                                                         // Break as there is no other overload available anyway
2317                                                         if (readMode) {
2318                                                                 if (!pe.PropertyInfo.HasGet || !pe.PropertyInfo.Get.IsAccessible (current_type))
2319                                                                         break;
2320
2321                                                                 pe.Getter = pe.PropertyInfo.Get;
2322                                                         } else {
2323                                                                 if (!pe.PropertyInfo.HasSet || !pe.PropertyInfo.Set.IsAccessible (current_type))
2324                                                                         break;
2325
2326                                                                 pe.Setter = pe.PropertyInfo.Set;
2327                                                         }
2328                                                 }
2329                                         }
2330
2331                                         // TODO: It's used by EventExpr -> FieldExpr transformation only
2332                                         // TODO: Should go to MemberAccess
2333                                         me = me.ResolveMemberAccess (rc, null, null);
2334
2335                                         if (Arity > 0) {
2336                                                 targs.Resolve (rc);
2337                                                 me.SetTypeArguments (rc, targs);
2338                                         }
2339
2340                                         return me;
2341                                 }
2342
2343                                 //
2344                                 // Stage 3: Lookup nested types, namespaces and type parameters in the context
2345                                 //
2346                                 if (!invocableOnly) {
2347                                         e = ResolveAsTypeStep (rc, lookup_arity == 0 || !errorMode);
2348                                         if (e != null)
2349                                                 return e;
2350                                 }
2351
2352                                 if (errorMode) {
2353                                         rc.Report.Error (103, loc, "The name `{0}' does not exist in the current context", Name);
2354                                         return null;
2355                                 }
2356
2357                                 if (RootContext.EvalMode) {
2358                                         var fi = Evaluator.LookupField (Name);
2359                                         if (fi != null)
2360                                                 return new FieldExpr (fi.Item1, loc);
2361                                 }
2362
2363                                 lookup_arity = 0;
2364                                 invocableOnly = false;
2365                                 errorMode = true;
2366                         }
2367                 }
2368
2369                 Expression SimpleNameResolve (ResolveContext ec, Expression right_side, bool intermediate)
2370                 {
2371                         Expression e = LookupNameExpression (ec, right_side == null, false);
2372
2373                         if (e == null)
2374                                 return null;
2375
2376                         if (right_side != null)
2377                                 e = e.ResolveLValue (ec, right_side);
2378                         else
2379                                 e = e.Resolve (ec);
2380
2381                         //if (ec.CurrentBlock == null || ec.CurrentBlock.CheckInvariantMeaningInBlock (Name, e, Location))
2382                         return e;
2383                 }
2384         }
2385
2386         /// <summary>
2387         ///   Represents a namespace or a type.  The name of the class was inspired by
2388         ///   section 10.8.1 (Fully Qualified Names).
2389         /// </summary>
2390         public abstract class FullNamedExpression : Expression
2391         {
2392                 protected override void CloneTo (CloneContext clonectx, Expression target)
2393                 {
2394                         // Do nothing, most unresolved type expressions cannot be
2395                         // resolved to different type
2396                 }
2397
2398                 public override Expression CreateExpressionTree (ResolveContext ec)
2399                 {
2400                         throw new NotSupportedException ("ET");
2401                 }
2402
2403                 public override FullNamedExpression ResolveAsTypeStep (IMemberContext ec, bool silent)
2404                 {
2405                         return this;
2406                 }
2407
2408                 public override void Emit (EmitContext ec)
2409                 {
2410                         throw new InternalErrorException ("FullNamedExpression `{0}' found in resolved tree",
2411                                 GetSignatureForError ());
2412                 }
2413         }
2414
2415         /// <summary>
2416         ///   Expression that evaluates to a type
2417         /// </summary>
2418         public abstract class TypeExpr : FullNamedExpression {
2419                 public override FullNamedExpression ResolveAsTypeStep (IMemberContext ec, bool silent)
2420                 {
2421                         TypeExpr t = DoResolveAsTypeStep (ec);
2422                         if (t == null)
2423                                 return null;
2424
2425                         eclass = ExprClass.Type;
2426                         return t;
2427                 }
2428
2429                 protected override Expression DoResolve (ResolveContext ec)
2430                 {
2431                         return ResolveAsTypeTerminal (ec, false);
2432                 }
2433
2434                 public virtual bool CheckAccessLevel (IMemberContext mc)
2435                 {
2436                         DeclSpace c = mc.CurrentMemberDefinition as DeclSpace;
2437                         if (c == null)
2438                                 c = mc.CurrentMemberDefinition.Parent;
2439
2440                         return c.CheckAccessLevel (Type);
2441                 }
2442
2443                 protected abstract TypeExpr DoResolveAsTypeStep (IMemberContext ec);
2444
2445                 public override bool Equals (object obj)
2446                 {
2447                         TypeExpr tobj = obj as TypeExpr;
2448                         if (tobj == null)
2449                                 return false;
2450
2451                         return Type == tobj.Type;
2452                 }
2453
2454                 public override int GetHashCode ()
2455                 {
2456                         return Type.GetHashCode ();
2457                 }
2458         }
2459
2460         /// <summary>
2461         ///   Fully resolved Expression that already evaluated to a type
2462         /// </summary>
2463         public class TypeExpression : TypeExpr {
2464                 public TypeExpression (TypeSpec t, Location l)
2465                 {
2466                         Type = t;
2467                         eclass = ExprClass.Type;
2468                         loc = l;
2469                 }
2470
2471                 protected override TypeExpr DoResolveAsTypeStep (IMemberContext ec)
2472                 {
2473                         return this;
2474                 }
2475
2476                 public override TypeExpr ResolveAsTypeTerminal (IMemberContext ec, bool silent)
2477                 {
2478                         return this;
2479                 }
2480         }
2481
2482         /// <summary>
2483         ///   This class denotes an expression which evaluates to a member
2484         ///   of a struct or a class.
2485         /// </summary>
2486         public abstract class MemberExpr : Expression
2487         {
2488                 //
2489                 // An instance expression associated with this member, if it's a
2490                 // non-static member
2491                 //
2492                 public Expression InstanceExpression;
2493
2494                 /// <summary>
2495                 ///   The name of this member.
2496                 /// </summary>
2497                 public abstract string Name {
2498                         get;
2499                 }
2500
2501                 //
2502                 // When base.member is used
2503                 //
2504                 public bool IsBase {
2505                         get { return InstanceExpression is BaseThis; }
2506                 }
2507
2508                 /// <summary>
2509                 ///   Whether this is an instance member.
2510                 /// </summary>
2511                 public abstract bool IsInstance {
2512                         get;
2513                 }
2514
2515                 /// <summary>
2516                 ///   Whether this is a static member.
2517                 /// </summary>
2518                 public abstract bool IsStatic {
2519                         get;
2520                 }
2521
2522                 // TODO: Not needed
2523                 protected abstract TypeSpec DeclaringType {
2524                         get;
2525                 }
2526
2527                 //
2528                 // Converts best base candidate for virtual method starting from QueriedBaseType
2529                 //
2530                 protected MethodSpec CandidateToBaseOverride (ResolveContext rc, MethodSpec method)
2531                 {
2532                         //
2533                         // Only when base.member is used and method is virtual
2534                         //
2535                         if (!IsBase)
2536                                 return method;
2537
2538                         //
2539                         // Overload resulution works on virtual or non-virtual members only (no overrides). That
2540                         // means for base.member access we have to find the closest match after we found best candidate
2541                         //
2542                         if ((method.Modifiers & (Modifiers.ABSTRACT | Modifiers.VIRTUAL | Modifiers.STATIC)) != Modifiers.STATIC) {
2543                                 //
2544                                 // The method could already be what we are looking for
2545                                 //
2546                                 TypeSpec[] targs = null;
2547                                 if (method.DeclaringType != InstanceExpression.Type) {
2548                                         var base_override = MemberCache.FindMember (InstanceExpression.Type, new MemberFilter (method), BindingRestriction.InstanceOnly) as MethodSpec;
2549                                         if (base_override != null && base_override.DeclaringType != method.DeclaringType) {
2550                                                 if (base_override.IsGeneric)
2551                                                         targs = method.TypeArguments;
2552
2553                                                 method = base_override;
2554                                         }
2555                                 }
2556
2557                                 // TODO: For now we do it for any hoisted call even if it's needed for
2558                                 // hoisted stories only but that requires a new expression wrapper
2559                                 if (rc.CurrentAnonymousMethod != null) {
2560                                         if (targs == null && method.IsGeneric) {
2561                                                 targs = method.TypeArguments;
2562                                                 method = method.GetGenericMethodDefinition ();
2563                                         }
2564
2565                                         if (method.Parameters.HasArglist)
2566                                                 throw new NotImplementedException ("__arglist base call proxy");
2567
2568                                         method = rc.CurrentMemberDefinition.Parent.PartialContainer.CreateHoistedBaseCallProxy (rc, method);
2569
2570                                         // Ideally this should apply to any proxy rewrite but in the case of unary mutators on
2571                                         // get/set member expressions second call would fail to proxy because left expression
2572                                         // would be of 'this' and not 'base'
2573                                         if (rc.CurrentType.IsStruct)
2574                                                 InstanceExpression = rc.GetThis (loc);
2575                                 }
2576
2577                                 if (targs != null)
2578                                         method = method.MakeGenericMethod (targs);
2579                         }
2580
2581                         //
2582                         // Only base will allow this invocation to happen.
2583                         //
2584                         if (method.IsAbstract) {
2585                                 Error_CannotCallAbstractBase (rc, method.GetSignatureForError ());
2586                         }
2587
2588                         return method;
2589                 }
2590
2591                 protected void CheckProtectedMemberAccess<T> (ResolveContext rc, T member) where T : MemberSpec
2592                 {
2593                         if (InstanceExpression == null)
2594                                 return;
2595
2596                         if ((member.Modifiers & Modifiers.AccessibilityMask) == Modifiers.PROTECTED && !(InstanceExpression is This)) {
2597                                 var ct = rc.CurrentType;
2598                                 var expr_type = InstanceExpression.Type;
2599                                 if (ct != expr_type) {
2600                                         expr_type = expr_type.GetDefinition ();
2601                                         if (ct != expr_type && !IsSameOrBaseQualifier (ct, expr_type)) {
2602                                                 rc.Report.SymbolRelatedToPreviousError (member);
2603                                                 rc.Report.Error (1540, loc,
2604                                                         "Cannot access protected member `{0}' via a qualifier of type `{1}'. The qualifier must be of type `{2}' or derived from it",
2605                                                         member.GetSignatureForError (), expr_type.GetSignatureForError (), ct.GetSignatureForError ());
2606                                         }
2607                                 }
2608                         }
2609                 }
2610
2611                 static bool IsSameOrBaseQualifier (TypeSpec type, TypeSpec qtype)
2612                 {
2613                         do {
2614                                 type = type.GetDefinition ();
2615
2616                                 if (type == qtype || TypeManager.IsFamilyAccessible (qtype, type))
2617                                         return true;
2618
2619                                 type = type.DeclaringType;
2620                         } while (type != null);
2621
2622                         return false;
2623                 }
2624
2625                 protected void DoBestMemberChecks<T> (ResolveContext rc, T member) where T : MemberSpec, IInterfaceMemberSpec
2626                 {
2627                         if (InstanceExpression != null) {
2628                                 InstanceExpression = InstanceExpression.Resolve (rc);
2629                                 CheckProtectedMemberAccess (rc, member);
2630                         }
2631
2632                         if (member.MemberType.IsPointer && !rc.IsUnsafe) {
2633                                 UnsafeError (rc, loc);
2634                         }
2635
2636                         if (!rc.IsObsolete) {
2637                                 ObsoleteAttribute oa = member.GetAttributeObsolete ();
2638                                 if (oa != null)
2639                                         AttributeTester.Report_ObsoleteMessage (oa, member.GetSignatureForError (), loc, rc.Report);
2640                         }
2641
2642                         if (!(member is FieldSpec))
2643                                 member.MemberDefinition.SetIsUsed ();
2644                 }
2645
2646                 protected virtual void Error_CannotCallAbstractBase (ResolveContext rc, string name)
2647                 {
2648                         rc.Report.Error (205, loc, "Cannot call an abstract base member `{0}'", name);
2649                 }
2650
2651                 //
2652                 // Implements identicial simple name and type-name
2653                 //
2654                 public Expression ProbeIdenticalTypeName (ResolveContext rc, Expression left, SimpleName name)
2655                 {
2656                         var t = left.Type;
2657                         if (t.Kind == MemberKind.InternalCompilerType || t is ElementTypeSpec || t.Arity > 0)
2658                                 return left;
2659
2660                         // In a member access of the form E.I, if E is a single identifier, and if the meaning of E as a simple-name is
2661                         // a constant, field, property, local variable, or parameter with the same type as the meaning of E as a type-name
2662
2663                         if (left is MemberExpr || left is VariableReference) {
2664                                 rc.Report.DisableReporting ();
2665                                 Expression identical_type = rc.LookupNamespaceOrType (name.Name, 0, loc, true) as TypeExpr;
2666                                 rc.Report.EnableReporting ();
2667                                 if (identical_type != null && identical_type.Type == left.Type)
2668                                         return identical_type;
2669                         }
2670
2671                         return left;
2672                 }
2673
2674                 public bool ResolveInstanceExpression (ResolveContext rc)
2675                 {
2676                         if (IsStatic) {
2677                                 if (InstanceExpression != null) {
2678                                         if (InstanceExpression is TypeExpr) {
2679                                                 ObsoleteAttribute oa = InstanceExpression.Type.GetAttributeObsolete ();
2680                                                 if (oa != null && !rc.IsObsolete) {
2681                                                         AttributeTester.Report_ObsoleteMessage (oa, InstanceExpression.GetSignatureForError (), loc, rc.Report);
2682                                                 }
2683                                         } else {
2684                                                 var runtime_expr = InstanceExpression as RuntimeValueExpression;
2685                                                 if (runtime_expr == null || !runtime_expr.IsSuggestionOnly) {
2686                                                         rc.Report.Error (176, loc,
2687                                                                 "Static member `{0}' cannot be accessed with an instance reference, qualify it with a type name instead",
2688                                                                 GetSignatureForError ());
2689                                                 }
2690                                         }
2691
2692                                         InstanceExpression = null;
2693                                 }
2694
2695                                 return false;
2696                         }
2697
2698                         if (InstanceExpression == null || InstanceExpression is TypeExpr) {
2699                                 if (InstanceExpression != null || !This.IsThisAvailable (rc, true)) {
2700                                         if (rc.HasSet (ResolveContext.Options.FieldInitializerScope))
2701                                                 rc.Report.Error (236, loc,
2702                                                         "A field initializer cannot reference the nonstatic field, method, or property `{0}'",
2703                                                         GetSignatureForError ());
2704                                         else
2705                                                 rc.Report.Error (120, loc,
2706                                                         "An object reference is required to access non-static member `{0}'",
2707                                                         GetSignatureForError ());
2708
2709                                         return false;
2710                                 }
2711
2712                                 if (!TypeManager.IsFamilyAccessible (rc.CurrentType, DeclaringType)) {
2713                                         rc.Report.Error (38, loc,
2714                                                 "Cannot access a nonstatic member of outer type `{0}' via nested type `{1}'",
2715                                                 DeclaringType.GetSignatureForError (), rc.CurrentType.GetSignatureForError ());
2716                                 }
2717
2718                                 InstanceExpression = rc.GetThis (loc);
2719                                 return false;
2720                         }
2721
2722                         var me = InstanceExpression as MemberExpr;
2723                         if (me != null) {
2724                                 me.ResolveInstanceExpression (rc);
2725
2726                                 var fe = me as FieldExpr;
2727                                 if (fe != null && fe.IsMarshalByRefAccess ()) {
2728                                         rc.Report.SymbolRelatedToPreviousError (me.DeclaringType);
2729                                         rc.Report.Warning (1690, 1, loc,
2730                                                 "Cannot call methods, properties, or indexers on `{0}' because it is a value type member of a marshal-by-reference class",
2731                                                 me.GetSignatureForError ());
2732                                 }
2733                         }
2734
2735                         return true;
2736                 }
2737
2738                 public virtual MemberExpr ResolveMemberAccess (ResolveContext ec, Expression left, SimpleName original)
2739                 {
2740                         if (left != null && left.IsNull && TypeManager.IsReferenceType (left.Type)) {
2741                                 ec.Report.Warning (1720, 1, left.Location,
2742                                         "Expression will always cause a `{0}'", "System.NullReferenceException");
2743                         }
2744
2745                         InstanceExpression = left;
2746                         return this;
2747                 }
2748
2749                 protected void EmitInstance (EmitContext ec, bool prepare_for_load)
2750                 {
2751                         TypeSpec instance_type = InstanceExpression.Type;
2752                         if (TypeManager.IsValueType (instance_type)) {
2753                                 if (InstanceExpression is IMemoryLocation) {
2754                                         ((IMemoryLocation) InstanceExpression).AddressOf (ec, AddressOp.LoadStore);
2755                                 } else {
2756                                         LocalTemporary t = new LocalTemporary (instance_type);
2757                                         InstanceExpression.Emit (ec);
2758                                         t.Store (ec);
2759                                         t.AddressOf (ec, AddressOp.Store);
2760                                 }
2761                         } else {
2762                                 InstanceExpression.Emit (ec);
2763
2764                                 // Only to make verifier happy
2765                                 if (instance_type.IsGenericParameter && !(InstanceExpression is This) && TypeManager.IsReferenceType (instance_type))
2766                                         ec.Emit (OpCodes.Box, instance_type);
2767                         }
2768
2769                         if (prepare_for_load)
2770                                 ec.Emit (OpCodes.Dup);
2771                 }
2772
2773                 public abstract void SetTypeArguments (ResolveContext ec, TypeArguments ta);
2774         }
2775
2776         //
2777         // Represents a group of extension method candidates for whole namespace
2778         //
2779         class ExtensionMethodGroupExpr : MethodGroupExpr, OverloadResolver.IErrorHandler
2780         {
2781                 NamespaceEntry namespace_entry;
2782                 public readonly Expression ExtensionExpression;
2783
2784                 public ExtensionMethodGroupExpr (IList<MethodSpec> list, NamespaceEntry n, Expression extensionExpr, Location l)
2785                         : base (list.Cast<MemberSpec>().ToList (), extensionExpr.Type, l)
2786                 {
2787                         this.namespace_entry = n;
2788                         this.ExtensionExpression = extensionExpr;
2789                 }
2790
2791                 public override bool IsStatic {
2792                         get { return true; }
2793                 }
2794
2795                 public override IList<MemberSpec> GetBaseMembers (TypeSpec baseType)
2796                 {
2797                         if (namespace_entry == null)
2798                                 return null;
2799
2800                         //
2801                         // For extension methodgroup we are not looking for base members but parent
2802                         // namespace extension methods
2803                         //
2804                         int arity = type_arguments == null ? 0 : type_arguments.Count;
2805                         var found = namespace_entry.LookupExtensionMethod (DeclaringType, Name, arity, ref namespace_entry);
2806                         if (found == null)
2807                                 return null;
2808
2809                         return found.Cast<MemberSpec> ().ToList ();
2810                 }
2811
2812                 public override MethodGroupExpr LookupExtensionMethod (ResolveContext rc)
2813                 {
2814                         // We are already here
2815                         return null;
2816                 }
2817
2818                 public override MethodGroupExpr OverloadResolve (ResolveContext ec, ref Arguments arguments, OverloadResolver.IErrorHandler ehandler, OverloadResolver.Restrictions restr)
2819                 {
2820                         if (arguments == null)
2821                                 arguments = new Arguments (1);
2822
2823                         arguments.Insert (0, new Argument (ExtensionExpression, Argument.AType.ExtensionType));
2824                         var res = base.OverloadResolve (ec, ref arguments, ehandler ?? this, restr);
2825
2826                         // Store resolved argument and restore original arguments
2827                         if (res == null) {
2828                                 // Clean-up modified arguments for error reporting
2829                                 arguments.RemoveAt (0);
2830                                 return null;
2831                         }
2832
2833                         var me = ExtensionExpression as MemberExpr;
2834                         if (me != null)
2835                                 me.ResolveInstanceExpression (ec);
2836
2837                         InstanceExpression = null;
2838                         return this;
2839                 }
2840
2841                 #region IErrorHandler Members
2842
2843                 bool OverloadResolver.IErrorHandler.AmbiguousCandidates (ResolveContext rc, MemberSpec best, MemberSpec ambiguous)
2844                 {
2845                         return false;
2846                 }
2847
2848                 bool OverloadResolver.IErrorHandler.ArgumentMismatch (ResolveContext rc, MemberSpec best, Argument arg, int index)
2849                 {
2850                         rc.Report.SymbolRelatedToPreviousError (best);
2851                         rc.Report.Error (1928, loc,
2852                                 "Type `{0}' does not contain a member `{1}' and the best extension method overload `{2}' has some invalid arguments",
2853                                 queried_type.GetSignatureForError (), Name, best.GetSignatureForError ());
2854
2855                         if (index == 0) {
2856                                 rc.Report.Error (1929, loc,
2857                                         "Extension method instance type `{0}' cannot be converted to `{1}'",
2858                                         arg.Type.GetSignatureForError (), ((MethodSpec)best).Parameters.ExtensionMethodType.GetSignatureForError ());
2859                         }
2860
2861                         return true;
2862                 }
2863
2864                 bool OverloadResolver.IErrorHandler.NoArgumentMatch (ResolveContext rc, MemberSpec best)
2865                 {
2866                         return false;
2867                 }
2868
2869                 bool OverloadResolver.IErrorHandler.TypeInferenceFailed (ResolveContext rc, MemberSpec best)
2870                 {
2871                         return false;
2872                 }
2873
2874                 #endregion
2875         }
2876
2877         /// <summary>
2878         ///   MethodGroupExpr represents a group of method candidates which
2879         ///   can be resolved to the best method overload
2880         /// </summary>
2881         public class MethodGroupExpr : MemberExpr, OverloadResolver.IBaseMembersProvider
2882         {
2883                 protected IList<MemberSpec> Methods;
2884                 MethodSpec best_candidate;
2885                 protected TypeArguments type_arguments;
2886
2887                 SimpleName simple_name;
2888                 protected TypeSpec queried_type;
2889
2890                 public MethodGroupExpr (IList<MemberSpec> mi, TypeSpec type, Location loc)
2891                 {
2892                         Methods = mi;
2893                         this.loc = loc;
2894                         this.type = InternalType.MethodGroup;
2895
2896                         eclass = ExprClass.MethodGroup;
2897                         queried_type = type;
2898                 }
2899
2900                 public MethodGroupExpr (MethodSpec m, TypeSpec type, Location loc)
2901                         : this (new MemberSpec[] { m }, type, loc)
2902                 {
2903                 }
2904
2905                 #region Properties
2906
2907                 public MethodSpec BestCandidate {
2908                         get {
2909                                 return best_candidate;
2910                         }
2911                 }
2912
2913                 protected override TypeSpec DeclaringType {
2914                         get {
2915                                 return queried_type;
2916                         }
2917                 }
2918
2919                 public override bool IsInstance {
2920                         get {
2921                                 if (best_candidate != null)
2922                                         return !best_candidate.IsStatic;
2923
2924                                 return false;
2925                         }
2926                 }
2927
2928                 public override bool IsStatic {
2929                         get {
2930                                 if (best_candidate != null)
2931                                         return best_candidate.IsStatic;
2932
2933                                 return false;
2934                         }
2935                 }
2936
2937                 public override string Name {
2938                         get {
2939                                 if (best_candidate != null)
2940                                         return best_candidate.Name;
2941
2942                                 // TODO: throw ?
2943                                 return Methods.First ().Name;
2944                         }
2945                 }
2946
2947                 #endregion
2948
2949                 //
2950                 // When best candidate is already know this factory can be used
2951                 // to avoid expensive overload resolution to be called
2952                 //
2953                 // NOTE: InstanceExpression has to be set manually
2954                 //
2955                 public static MethodGroupExpr CreatePredefined (MethodSpec best, TypeSpec queriedType, Location loc)
2956                 {
2957                         return new MethodGroupExpr (best, queriedType, loc) {
2958                                 best_candidate = best
2959                         };
2960                 }
2961
2962                 public override string GetSignatureForError ()
2963                 {
2964                         if (best_candidate != null)
2965                                 return best_candidate.GetSignatureForError ();
2966
2967                         return Methods.First ().GetSignatureForError ();
2968                 }
2969
2970                 public override Expression CreateExpressionTree (ResolveContext ec)
2971                 {
2972                         if (best_candidate == null) {
2973                                 ec.Report.Error (1953, loc, "An expression tree cannot contain an expression with method group");
2974                                 return null;
2975                         }
2976
2977                         if (best_candidate.IsConditionallyExcluded (loc))
2978                                 ec.Report.Error (765, loc,
2979                                         "Partial methods with only a defining declaration or removed conditional methods cannot be used in an expression tree");
2980
2981                         return new TypeOfMethod (best_candidate, loc);
2982                 }
2983
2984                 protected override Expression DoResolve (ResolveContext ec)
2985                 {
2986                         this.eclass = ExprClass.MethodGroup;
2987
2988                         if (InstanceExpression != null) {
2989                                 InstanceExpression = InstanceExpression.Resolve (ec);
2990                                 if (InstanceExpression == null)
2991                                         return null;
2992                         }
2993
2994                         return this;
2995                 }
2996
2997                 public override void Emit (EmitContext ec)
2998                 {
2999                         throw new NotSupportedException ();
3000                 }
3001
3002                 public void EmitCall (EmitContext ec, Arguments arguments)
3003                 {
3004                         Invocation.EmitCall (ec, InstanceExpression, best_candidate, arguments, loc);
3005                 }
3006
3007                 public override void Error_ValueCannotBeConverted (ResolveContext ec, Location loc, TypeSpec target, bool expl)
3008                 {
3009                         ec.Report.Error (428, loc, "Cannot convert method group `{0}' to non-delegate type `{1}'. Consider using parentheses to invoke the method",
3010                                 Name, TypeManager.CSharpName (target));
3011                 }
3012
3013                 public static bool IsExtensionMethodArgument (Expression expr)
3014                 {
3015                         //
3016                         // LAMESPEC: No details about which expressions are not allowed
3017                         //
3018                         return !(expr is BaseThis);
3019                 }
3020
3021                 /// <summary>
3022                 ///   Find the Applicable Function Members (7.4.2.1)
3023                 ///
3024                 ///   me: Method Group expression with the members to select.
3025                 ///       it might contain constructors or methods (or anything
3026                 ///       that maps to a method).
3027                 ///
3028                 ///   Arguments: ArrayList containing resolved Argument objects.
3029                 ///
3030                 ///   loc: The location if we want an error to be reported, or a Null
3031                 ///        location for "probing" purposes.
3032                 ///
3033                 ///   Returns: The MethodBase (either a ConstructorInfo or a MethodInfo)
3034                 ///            that is the best match of me on Arguments.
3035                 ///
3036                 /// </summary>
3037                 public virtual MethodGroupExpr OverloadResolve (ResolveContext ec, ref Arguments args, OverloadResolver.IErrorHandler cerrors, OverloadResolver.Restrictions restr)
3038                 {
3039                         // TODO: causes issues with probing mode, remove explicit Kind check
3040                         if (best_candidate != null && best_candidate.Kind == MemberKind.Destructor)
3041                                 return this;
3042
3043                         var r = new OverloadResolver (Methods, type_arguments, restr, loc);
3044                         if ((restr & OverloadResolver.Restrictions.NoBaseMembers) == 0) {
3045                                 r.BaseMembersProvider = this;
3046                         }
3047
3048                         if (cerrors != null)
3049                                 r.CustomErrors = cerrors;
3050
3051                         // TODO: When in probing mode do IsApplicable only and when called again do VerifyArguments for full error reporting
3052                         best_candidate = r.ResolveMember<MethodSpec> (ec, ref args);
3053                         if (best_candidate == null)
3054                                 return r.BestCandidateIsDynamic ? this : null;
3055
3056                         // Overload resolver had to create a new method group, all checks bellow have already been executed
3057                         if (r.BestCandidateNewMethodGroup != null)
3058                                 return r.BestCandidateNewMethodGroup;
3059
3060                         if (best_candidate.Kind == MemberKind.Method) {
3061                                 if (InstanceExpression != null) {
3062                                         if (best_candidate.IsExtensionMethod && args[0].Expr == InstanceExpression) {
3063                                                 InstanceExpression = null;
3064                                         } else {
3065                                                 if (best_candidate.IsStatic && simple_name != null) {
3066                                                         InstanceExpression = ProbeIdenticalTypeName (ec, InstanceExpression, simple_name);
3067                                                 }
3068
3069                                                 InstanceExpression.Resolve (ec);
3070                                         }
3071                                 }
3072
3073                                 ResolveInstanceExpression (ec);
3074                                 if (InstanceExpression != null)
3075                                         CheckProtectedMemberAccess (ec, best_candidate);
3076
3077                                 if (best_candidate.IsGeneric) {
3078                                         ConstraintChecker.CheckAll (ec.MemberContext, best_candidate.GetGenericMethodDefinition (), best_candidate.TypeArguments,
3079                                                 best_candidate.Constraints, loc);
3080                                 }
3081                         }
3082
3083                         best_candidate = CandidateToBaseOverride (ec, best_candidate);
3084                         return this;
3085                 }
3086
3087                 public override MemberExpr ResolveMemberAccess (ResolveContext ec, Expression left, SimpleName original)
3088                 {
3089                         simple_name = original;
3090                         return base.ResolveMemberAccess (ec, left, original);
3091                 }
3092
3093                 public override void SetTypeArguments (ResolveContext ec, TypeArguments ta)
3094                 {
3095                         type_arguments = ta;
3096                 }
3097
3098                 #region IBaseMembersProvider Members
3099
3100                 public virtual IList<MemberSpec> GetBaseMembers (TypeSpec baseType)
3101                 {
3102                         return baseType == null ? null : MemberCache.FindMembers (baseType, Methods [0].Name, false);
3103                 }
3104
3105                 //
3106                 // Extension methods lookup after ordinary methods candidates failed to apply
3107                 //
3108                 public virtual MethodGroupExpr LookupExtensionMethod (ResolveContext rc)
3109                 {
3110                         if (InstanceExpression == null)
3111                                 return null;
3112
3113                         InstanceExpression = InstanceExpression.Resolve (rc);
3114                         if (!IsExtensionMethodArgument (InstanceExpression))
3115                                 return null;
3116
3117                         int arity = type_arguments == null ? 0 : type_arguments.Count;
3118                         NamespaceEntry methods_scope = null;
3119                         var methods = rc.LookupExtensionMethod (InstanceExpression.Type, Methods[0].Name, arity, ref methods_scope);
3120                         if (methods == null)
3121                                 return null;
3122
3123                         var emg = new ExtensionMethodGroupExpr (methods, methods_scope, InstanceExpression, loc);
3124                         emg.SetTypeArguments (rc, type_arguments);
3125                         return emg;
3126                 }
3127
3128                 #endregion
3129         }
3130
3131         public struct OverloadResolver
3132         {
3133                 [Flags]
3134                 public enum Restrictions
3135                 {
3136                         None = 0,
3137                         DelegateInvoke = 1,
3138                         ProbingOnly     = 1 << 1,
3139                         Covariant = 1 << 2,
3140                         NoBaseMembers = 1 << 3
3141                 }
3142
3143                 public interface IBaseMembersProvider
3144                 {
3145                         IList<MemberSpec> GetBaseMembers (TypeSpec baseType);
3146                         MethodGroupExpr LookupExtensionMethod (ResolveContext rc);
3147                 }
3148
3149                 public interface IErrorHandler
3150                 {
3151                         bool AmbiguousCandidates (ResolveContext rc, MemberSpec best, MemberSpec ambiguous);
3152                         bool ArgumentMismatch (ResolveContext rc, MemberSpec best, Argument a, int index);
3153                         bool NoArgumentMatch (ResolveContext rc, MemberSpec best);
3154                         bool TypeInferenceFailed (ResolveContext rc, MemberSpec best);
3155                 }
3156
3157                 sealed class NoBaseMembers : IBaseMembersProvider
3158                 {
3159                         public static readonly IBaseMembersProvider Instance = new NoBaseMembers ();
3160
3161                         public IList<MemberSpec> GetBaseMembers (TypeSpec baseType)
3162                         {
3163                                 return null;
3164                         }
3165
3166                         public MethodGroupExpr LookupExtensionMethod (ResolveContext rc)
3167                         {
3168                                 return null;
3169                         }
3170                 }
3171
3172                 struct AmbiguousCandidate
3173                 {
3174                         public readonly MemberSpec Member;
3175                         public readonly bool Expanded;
3176
3177                         public AmbiguousCandidate (MemberSpec member, bool expanded)
3178                         {
3179                                 Member = member;
3180                                 Expanded = expanded;
3181                         }
3182                 }
3183
3184                 Location loc;
3185                 IList<MemberSpec> members;
3186                 TypeArguments type_arguments;
3187                 IBaseMembersProvider base_provider;
3188                 IErrorHandler custom_errors;
3189                 Restrictions restrictions;
3190                 MethodGroupExpr best_candidate_extension_group;
3191
3192                 SessionReportPrinter lambda_conv_msgs;
3193                 ReportPrinter prev_recorder;
3194
3195                 public OverloadResolver (IList<MemberSpec> members, Restrictions restrictions, Location loc)
3196                         : this (members, null, restrictions, loc)
3197                 {
3198                 }
3199
3200                 public OverloadResolver (IList<MemberSpec> members, TypeArguments targs, Restrictions restrictions, Location loc)
3201                         : this ()
3202                 {
3203                         if (members == null || members.Count == 0)
3204                                 throw new ArgumentException ("empty members set");
3205
3206                         this.members = members;
3207                         this.loc = loc;
3208                         type_arguments = targs;
3209                         this.restrictions = restrictions;
3210                         if (IsDelegateInvoke)
3211                                 this.restrictions |= Restrictions.NoBaseMembers;
3212
3213                         base_provider = NoBaseMembers.Instance;
3214                 }
3215
3216                 #region Properties
3217
3218                 public IBaseMembersProvider BaseMembersProvider {
3219                         get {
3220                                 return base_provider;
3221                         }
3222                         set {
3223                                 base_provider = value;
3224                         }
3225                 }
3226
3227                 public bool BestCandidateIsDynamic { get; set; }
3228
3229                 //
3230                 // Best candidate was found in newly created MethodGroupExpr, used by extension methods
3231                 //
3232                 public MethodGroupExpr BestCandidateNewMethodGroup {
3233                         get {
3234                                 return best_candidate_extension_group;
3235                         }
3236                 }
3237
3238                 public IErrorHandler CustomErrors {
3239                         get {
3240                                 return custom_errors;
3241                         }
3242                         set {
3243                                 custom_errors = value;
3244                         }
3245                 }
3246
3247                 TypeSpec DelegateType {
3248                         get {
3249                                 if ((restrictions & Restrictions.DelegateInvoke) == 0)
3250                                         throw new InternalErrorException ("Not running in delegate mode", loc);
3251
3252                                 return members [0].DeclaringType;
3253                         }
3254                 }
3255
3256                 bool IsProbingOnly {
3257                         get {
3258                                 return (restrictions & Restrictions.ProbingOnly) != 0;
3259                         }
3260                 }
3261
3262                 bool IsDelegateInvoke {
3263                         get {
3264                                 return (restrictions & Restrictions.DelegateInvoke) != 0;
3265                         }
3266                 }
3267
3268                 #endregion
3269
3270                 //
3271                 //  7.4.3.3  Better conversion from expression
3272                 //  Returns :   1    if a->p is better,
3273                 //              2    if a->q is better,
3274                 //              0 if neither is better
3275                 //
3276                 static int BetterExpressionConversion (ResolveContext ec, Argument a, TypeSpec p, TypeSpec q)
3277                 {
3278                         TypeSpec argument_type = a.Type;
3279                         if (argument_type == InternalType.AnonymousMethod && RootContext.Version > LanguageVersion.ISO_2) {
3280                                 //
3281                                 // Uwrap delegate from Expression<T>
3282                                 //
3283                                 if (p.GetDefinition () == TypeManager.expression_type) {
3284                                         p = TypeManager.GetTypeArguments (p)[0];
3285                                 }
3286                                 if (q.GetDefinition () == TypeManager.expression_type) {
3287                                         q = TypeManager.GetTypeArguments (q)[0];
3288                                 }
3289
3290                                 p = Delegate.GetInvokeMethod (ec.Compiler, p).ReturnType;
3291                                 q = Delegate.GetInvokeMethod (ec.Compiler, q).ReturnType;
3292                                 if (p == TypeManager.void_type && q != TypeManager.void_type)
3293                                         return 2;
3294                                 if (q == TypeManager.void_type && p != TypeManager.void_type)
3295                                         return 1;
3296                         } else {
3297                                 if (argument_type == p)
3298                                         return 1;
3299
3300                                 if (argument_type == q)
3301                                         return 2;
3302                         }
3303
3304                         return BetterTypeConversion (ec, p, q);
3305                 }
3306
3307                 //
3308                 // 7.4.3.4  Better conversion from type
3309                 //
3310                 public static int BetterTypeConversion (ResolveContext ec, TypeSpec p, TypeSpec q)
3311                 {
3312                         if (p == null || q == null)
3313                                 throw new InternalErrorException ("BetterTypeConversion got a null conversion");
3314
3315                         if (p == TypeManager.int32_type) {
3316                                 if (q == TypeManager.uint32_type || q == TypeManager.uint64_type)
3317                                         return 1;
3318                         } else if (p == TypeManager.int64_type) {
3319                                 if (q == TypeManager.uint64_type)
3320                                         return 1;
3321                         } else if (p == TypeManager.sbyte_type) {
3322                                 if (q == TypeManager.byte_type || q == TypeManager.ushort_type ||
3323                                         q == TypeManager.uint32_type || q == TypeManager.uint64_type)
3324                                         return 1;
3325                         } else if (p == TypeManager.short_type) {
3326                                 if (q == TypeManager.ushort_type || q == TypeManager.uint32_type ||
3327                                         q == TypeManager.uint64_type)
3328                                         return 1;
3329                         } else if (p == InternalType.Dynamic) {
3330                                 if (q == TypeManager.object_type)
3331                                         return 2;
3332                         }
3333
3334                         if (q == TypeManager.int32_type) {
3335                                 if (p == TypeManager.uint32_type || p == TypeManager.uint64_type)
3336                                         return 2;
3337                         } if (q == TypeManager.int64_type) {
3338                                 if (p == TypeManager.uint64_type)
3339                                         return 2;
3340                         } else if (q == TypeManager.sbyte_type) {
3341                                 if (p == TypeManager.byte_type || p == TypeManager.ushort_type ||
3342                                         p == TypeManager.uint32_type || p == TypeManager.uint64_type)
3343                                         return 2;
3344                         } if (q == TypeManager.short_type) {
3345                                 if (p == TypeManager.ushort_type || p == TypeManager.uint32_type ||
3346                                         p == TypeManager.uint64_type)
3347                                         return 2;
3348                         } else if (q == InternalType.Dynamic) {
3349                                 if (p == TypeManager.object_type)
3350                                         return 1;
3351                         }
3352
3353                         // TODO: this is expensive
3354                         Expression p_tmp = new EmptyExpression (p);
3355                         Expression q_tmp = new EmptyExpression (q);
3356
3357                         bool p_to_q = Convert.ImplicitConversionExists (ec, p_tmp, q);
3358                         bool q_to_p = Convert.ImplicitConversionExists (ec, q_tmp, p);
3359
3360                         if (p_to_q && !q_to_p)
3361                                 return 1;
3362
3363                         if (q_to_p && !p_to_q)
3364                                 return 2;
3365
3366                         return 0;
3367                 }
3368
3369                 /// <summary>
3370                 ///   Determines "Better function" between candidate
3371                 ///   and the current best match
3372                 /// </summary>
3373                 /// <remarks>
3374                 ///    Returns a boolean indicating :
3375                 ///     false if candidate ain't better
3376                 ///     true  if candidate is better than the current best match
3377                 /// </remarks>
3378                 static bool BetterFunction (ResolveContext ec, Arguments args, MemberSpec candidate, bool candidate_params,
3379                         MemberSpec best, bool best_params)
3380                 {
3381                         AParametersCollection candidate_pd = ((IParametersMember) candidate).Parameters;
3382                         AParametersCollection best_pd = ((IParametersMember) best).Parameters;
3383
3384                         bool better_at_least_one = false;
3385                         bool same = true;
3386                         int args_count = args == null ? 0 : args.Count;
3387                         int j = 0;
3388                         for (int c_idx = 0, b_idx = 0; j < args_count; ++j, ++c_idx, ++b_idx) {
3389                                 Argument a = args[j];
3390
3391                                 // Default arguments are ignored for better decision
3392                                 if (a.IsDefaultArgument)
3393                                         break;
3394
3395                                 TypeSpec ct = candidate_pd.Types[c_idx];
3396                                 TypeSpec bt = best_pd.Types[b_idx];
3397
3398                                 if (candidate_params && candidate_pd.FixedParameters[c_idx].ModFlags == Parameter.Modifier.PARAMS) {
3399                                         ct = TypeManager.GetElementType (ct);
3400                                         --c_idx;
3401                                 }
3402
3403                                 if (best_params && best_pd.FixedParameters[b_idx].ModFlags == Parameter.Modifier.PARAMS) {
3404                                         bt = TypeManager.GetElementType (bt);
3405                                         --b_idx;
3406                                 }
3407
3408                                 if (ct == bt)
3409                                         continue;
3410
3411                                 same = false;
3412                                 int result = BetterExpressionConversion (ec, a, ct, bt);
3413
3414                                 // for each argument, the conversion to 'ct' should be no worse than
3415                                 // the conversion to 'bt'.
3416                                 if (result == 2)
3417                                         return false;
3418
3419                                 // for at least one argument, the conversion to 'ct' should be better than
3420                                 // the conversion to 'bt'.
3421                                 if (result != 0)
3422                                         better_at_least_one = true;
3423                         }
3424
3425                         if (better_at_least_one)
3426                                 return true;
3427
3428                         //
3429                         // This handles the case
3430                         //
3431                         //   Add (float f1, float f2, float f3);
3432                         //   Add (params decimal [] foo);
3433                         //
3434                         // The call Add (3, 4, 5) should be ambiguous.  Without this check, the
3435                         // first candidate would've chosen as better.
3436                         //
3437                         if (!same)
3438                                 return false;
3439
3440                         //
3441                         // The two methods have equal non-optional parameter types, apply tie-breaking rules
3442                         //
3443
3444                         //
3445                         // This handles the following cases:
3446                         //
3447                         //  Foo (int i) is better than Foo (int i, long l = 0)
3448                         //  Foo (params int[] args) is better than Foo (int i = 0, params int[] args)
3449                         //
3450                         // Prefer non-optional version
3451                         //
3452                         // LAMESPEC: Specification claims this should be done at last but the opposite is true
3453                         if (candidate_params == best_params && candidate_pd.Count != best_pd.Count) {
3454                                 if (candidate_pd.Count >= best_pd.Count)
3455                                         return false;
3456
3457                                 if (j < candidate_pd.Count && candidate_pd.FixedParameters[j].HasDefaultValue)
3458                                         return false;
3459
3460                                 return true;
3461                         }
3462
3463                         //
3464                         // One is a non-generic method and second is a generic method, then non-generic is better
3465                         //
3466                         if (best.IsGeneric != candidate.IsGeneric)
3467                                 return best.IsGeneric;
3468
3469                         //
3470                         // This handles the following cases:
3471                         //
3472                         //   Trim () is better than Trim (params char[] chars)
3473                         //   Concat (string s1, string s2, string s3) is better than
3474                         //     Concat (string s1, params string [] srest)
3475                         //   Foo (int, params int [] rest) is better than Foo (params int [] rest)
3476                         //
3477                         // Prefer non-expanded version
3478                         //
3479                         if (candidate_params != best_params)
3480                                 return best_params;
3481
3482                         int candidate_param_count = candidate_pd.Count;
3483                         int best_param_count = best_pd.Count;
3484
3485                         if (candidate_param_count != best_param_count)
3486                                 // can only happen if (candidate_params && best_params)
3487                                 return candidate_param_count > best_param_count && best_pd.HasParams;
3488
3489                         //
3490                         // Both methods have the same number of parameters, and the parameters have equal types
3491                         // Pick the "more specific" signature using rules over original (non-inflated) types
3492                         //
3493                         var candidate_def_pd = ((IParametersMember) candidate.MemberDefinition).Parameters;
3494                         var best_def_pd = ((IParametersMember) best.MemberDefinition).Parameters;
3495
3496                         bool specific_at_least_once = false;
3497                         for (j = 0; j < candidate_param_count; ++j) {
3498                                 var ct = candidate_def_pd.Types[j];
3499                                 var bt = best_def_pd.Types[j];
3500                                 if (ct == bt)
3501                                         continue;
3502                                 TypeSpec specific = MoreSpecific (ct, bt);
3503                                 if (specific == bt)
3504                                         return false;
3505                                 if (specific == ct)
3506                                         specific_at_least_once = true;
3507                         }
3508
3509                         if (specific_at_least_once)
3510                                 return true;
3511
3512                         // FIXME: handle lifted operators
3513                         // ...
3514
3515                         return false;
3516                 }
3517
3518                 public static void Error_ConstructorMismatch (ResolveContext rc, TypeSpec type, int argCount, Location loc)
3519                 {
3520                         rc.Report.Error (1729, loc,
3521                                 "The type `{0}' does not contain a constructor that takes `{1}' arguments",
3522                                 type.GetSignatureForError (), argCount.ToString ());
3523                 }
3524
3525                 ///
3526                 /// Determines if the candidate method is applicable (section 14.4.2.1)
3527                 /// to the given set of arguments
3528                 /// A return value rates candidate method compatibility,
3529                 /// 0 = the best, int.MaxValue = the worst
3530                 ///
3531                 int IsApplicable (ResolveContext ec, ref Arguments arguments, int arg_count, ref MemberSpec candidate, ref bool params_expanded_form)
3532                 {
3533                         AParametersCollection pd = ((IParametersMember) candidate).Parameters;
3534                         int param_count = pd.Count;
3535                         int optional_count = 0;
3536
3537                         if (arg_count != param_count) {
3538                                 for (int i = 0; i < pd.Count; ++i) {
3539                                         if (pd.FixedParameters[i].HasDefaultValue) {
3540                                                 optional_count = pd.Count - i;
3541                                                 break;
3542                                         }
3543                                 }
3544
3545                                 int args_gap = System.Math.Abs (arg_count - param_count);
3546                                 if (optional_count != 0) {
3547                                         if (args_gap > optional_count)
3548                                                 return int.MaxValue - 10000 + args_gap - optional_count;
3549
3550                                         // Readjust expected number when params used
3551                                         if (pd.HasParams) {
3552                                                 optional_count--;
3553                                                 if (arg_count < param_count)
3554                                                         param_count--;
3555                                         } else if (arg_count > param_count) {
3556                                                 return int.MaxValue - 10000 + args_gap;
3557                                         }
3558                                 } else if (arg_count != param_count) {
3559                                         if (!pd.HasParams)
3560                                                 return int.MaxValue - 10000 + args_gap;
3561                                         if (arg_count < param_count - 1)
3562                                                 return int.MaxValue - 10000 + args_gap;
3563                                 }
3564
3565                                 // Initialize expanded form of a method with 1 params parameter
3566                                 params_expanded_form = param_count == 1 && pd.HasParams;
3567
3568                                 // Resize to fit optional arguments
3569                                 if (optional_count != 0) {
3570                                         Arguments resized;
3571                                         if (arguments == null) {
3572                                                 resized = new Arguments (optional_count);
3573                                         } else {
3574                                                 resized = new Arguments (param_count);
3575                                                 resized.AddRange (arguments);
3576                                         }
3577
3578                                         for (int i = arg_count; i < param_count; ++i)
3579                                                 resized.Add (null);
3580                                         arguments = resized;
3581                                 }
3582                         }
3583
3584                         if (arg_count > 0) {
3585                                 //
3586                                 // Shuffle named arguments to the right positions if there are any
3587                                 //
3588                                 if (arguments[arg_count - 1] is NamedArgument) {
3589                                         arg_count = arguments.Count;
3590
3591                                         for (int i = 0; i < arg_count; ++i) {
3592                                                 bool arg_moved = false;
3593                                                 while (true) {
3594                                                         NamedArgument na = arguments[i] as NamedArgument;
3595                                                         if (na == null)
3596                                                                 break;
3597
3598                                                         int index = pd.GetParameterIndexByName (na.Name);
3599
3600                                                         // Named parameter not found or already reordered
3601                                                         if (index <= i)
3602                                                                 break;
3603
3604                                                         // When using parameters which should not be available to the user
3605                                                         if (index >= param_count)
3606                                                                 break;
3607
3608                                                         if (!arg_moved) {
3609                                                                 arguments.MarkReorderedArgument (na);
3610                                                                 arg_moved = true;
3611                                                         }
3612
3613                                                         Argument temp = arguments[index];
3614                                                         arguments[index] = arguments[i];
3615                                                         arguments[i] = temp;
3616
3617                                                         if (temp == null)
3618                                                                 break;
3619                                                 }
3620                                         }
3621                                 } else {
3622                                         arg_count = arguments.Count;
3623                                 }
3624                         } else if (arguments != null) {
3625                                 arg_count = arguments.Count;
3626                         }
3627
3628                         //
3629                         // 1. Handle generic method using type arguments when specified or type inference
3630                         //
3631                         var ms = candidate as MethodSpec;
3632                         if (ms != null && ms.IsGeneric) {
3633                                 if (type_arguments != null) {
3634                                         var g_args_count = ms.Arity;
3635                                         if (g_args_count != type_arguments.Count)
3636                                                 return int.MaxValue - 20000 + System.Math.Abs (type_arguments.Count - g_args_count);
3637
3638                                         candidate = ms = ms.MakeGenericMethod (type_arguments.Arguments);
3639                                         pd = ms.Parameters;
3640                                 } else {
3641                                         // TODO: It should not be here (we don't know yet whether any argument is lambda) but
3642                                         // for now it simplifies things. I should probably add a callback to ResolveContext
3643                                         if (lambda_conv_msgs == null) {
3644                                                 lambda_conv_msgs = new SessionReportPrinter ();
3645                                                 prev_recorder = ec.Report.SetPrinter (lambda_conv_msgs);
3646                                         }
3647
3648                                         int score = TypeManager.InferTypeArguments (ec, arguments, ref ms);
3649                                         lambda_conv_msgs.EndSession ();
3650
3651                                         if (score != 0)
3652                                                 return score - 20000;
3653
3654                                         candidate = ms;
3655                                         pd = ms.Parameters;
3656                                 }
3657                         } else {
3658                                 if (type_arguments != null)
3659                                         return int.MaxValue - 15000;
3660                         }
3661
3662                         //
3663                         // 2. Each argument has to be implicitly convertible to method parameter
3664                         //
3665                         Parameter.Modifier p_mod = 0;
3666                         TypeSpec pt = null;
3667                         for (int i = 0; i < arg_count; i++) {
3668                                 Argument a = arguments[i];
3669                                 if (a == null) {
3670                                         if (!pd.FixedParameters[i].HasDefaultValue)
3671                                                 throw new InternalErrorException ();
3672
3673                                         Expression e = pd.FixedParameters[i].DefaultValue as Constant;
3674                                         if (e == null)
3675                                                 e = new DefaultValueExpression (new TypeExpression (pd.Types[i], loc), loc).Resolve (ec);
3676
3677                                         arguments[i] = new Argument (e, Argument.AType.Default);
3678                                         continue;
3679                                 }
3680
3681                                 if (p_mod != Parameter.Modifier.PARAMS) {
3682                                         p_mod = pd.FixedParameters[i].ModFlags & ~(Parameter.Modifier.OUTMASK | Parameter.Modifier.REFMASK);
3683                                         pt = pd.Types[i];
3684                                 } else {
3685                                         params_expanded_form = true;
3686                                 }
3687
3688                                 Parameter.Modifier a_mod = a.Modifier & ~(Parameter.Modifier.OUTMASK | Parameter.Modifier.REFMASK);
3689                                 int score = 1;
3690                                 if (!params_expanded_form)
3691                                         score = IsArgumentCompatible (ec, a_mod, a, p_mod & ~Parameter.Modifier.PARAMS, pt);
3692
3693                                 //
3694                                 // It can be applicable in expanded form (when not doing exact match like for delegates)
3695                                 //
3696                                 if (score != 0 && (p_mod & Parameter.Modifier.PARAMS) != 0 && (restrictions & Restrictions.Covariant) == 0) {
3697                                         score = IsArgumentCompatible (ec, a_mod, a, 0, TypeManager.GetElementType (pt));
3698                                         if (score == 0)
3699                                                 params_expanded_form = true;
3700                                 }
3701
3702                                 if (score != 0) {
3703                                         if (params_expanded_form)
3704                                                 ++score;
3705                                         return (arg_count - i) * 2 + score;
3706                                 }
3707                         }
3708
3709                         if (arg_count != pd.Count)
3710                                 params_expanded_form = true;
3711
3712                         return 0;
3713                 }
3714
3715                 int IsArgumentCompatible (ResolveContext ec, Parameter.Modifier arg_mod, Argument argument, Parameter.Modifier param_mod, TypeSpec parameter)
3716                 {
3717                         //
3718                         // Types have to be identical when ref or out modifer is used
3719                         //
3720                         if ((arg_mod | param_mod) != 0) {
3721                                 if (argument.Type != parameter && !TypeSpecComparer.IsEqual (argument.Type, parameter)) {
3722                                         return 2;
3723                                 }
3724                         } else {
3725                                 //
3726                                 // Deploy custom error reporting for lambda methods. When probing lambda methods
3727                                 // keep all errors reported in separate set and once we are done and no best
3728                                 // candidate found, this set is used to report more details about what was wrong
3729                                 // with lambda body
3730                                 //
3731                                 if (argument.Expr.Type == InternalType.AnonymousMethod) {
3732                                         if (lambda_conv_msgs == null) {
3733                                                 lambda_conv_msgs = new SessionReportPrinter ();
3734                                                 prev_recorder = ec.Report.SetPrinter (lambda_conv_msgs);
3735                                         }
3736                                 }
3737
3738                                 if (!Convert.ImplicitConversionExists (ec, argument.Expr, parameter)) {
3739                                         if (lambda_conv_msgs != null) {
3740                                                 lambda_conv_msgs.EndSession ();
3741                                         }
3742
3743                                         if (argument.Type == InternalType.Dynamic)
3744                                                 return 0;
3745
3746                                         return 2;
3747                                 }
3748                         }
3749
3750                         if (arg_mod != param_mod)
3751                                 return 1;
3752
3753                         return 0;
3754                 }
3755
3756                 static TypeSpec MoreSpecific (TypeSpec p, TypeSpec q)
3757                 {
3758                         if (TypeManager.IsGenericParameter (p) && !TypeManager.IsGenericParameter (q))
3759                                 return q;
3760                         if (!TypeManager.IsGenericParameter (p) && TypeManager.IsGenericParameter (q))
3761                                 return p;
3762
3763                         var ac_p = p as ArrayContainer;
3764                         if (ac_p != null) {
3765                                 var ac_q = ((ArrayContainer) q);
3766                                 TypeSpec specific = MoreSpecific (ac_p.Element, ac_q.Element);
3767                                 if (specific == ac_p.Element)
3768                                         return p;
3769                                 if (specific == ac_q.Element)
3770                                         return q;
3771                         } else if (TypeManager.IsGenericType (p)) {
3772                                 var pargs = TypeManager.GetTypeArguments (p);
3773                                 var qargs = TypeManager.GetTypeArguments (q);
3774
3775                                 bool p_specific_at_least_once = false;
3776                                 bool q_specific_at_least_once = false;
3777
3778                                 for (int i = 0; i < pargs.Length; i++) {
3779                                         TypeSpec specific = MoreSpecific (pargs[i], qargs[i]);
3780                                         if (specific == pargs[i])
3781                                                 p_specific_at_least_once = true;
3782                                         if (specific == qargs[i])
3783                                                 q_specific_at_least_once = true;
3784                                 }
3785
3786                                 if (p_specific_at_least_once && !q_specific_at_least_once)
3787                                         return p;
3788                                 if (!p_specific_at_least_once && q_specific_at_least_once)
3789                                         return q;
3790                         }
3791
3792                         return null;
3793                 }
3794
3795                 //
3796                 // Find the best method from candidate list
3797                 //
3798                 public T ResolveMember<T> (ResolveContext rc, ref Arguments args) where T : MemberSpec, IParametersMember
3799                 {
3800                         List<AmbiguousCandidate> ambiguous_candidates = null;
3801
3802                         MemberSpec best_candidate;
3803                         Arguments best_candidate_args = null;
3804                         bool best_candidate_params = false;
3805                         int best_candidate_rate;
3806
3807                         int args_count = args != null ? args.Count : 0;
3808                         Arguments candidate_args = args;
3809                         bool error_mode = false;
3810                         var current_type = rc.CurrentType;
3811                         MemberSpec invocable_member = null;
3812
3813                         // Be careful, cannot return until error reporter is restored
3814                         while (true) {
3815                                 best_candidate = null;
3816                                 best_candidate_rate = int.MaxValue;
3817
3818                                 var type_members = members;
3819                                 try {
3820
3821                                         do {
3822                                                 for (int i = 0; i < type_members.Count; ++i) {
3823                                                         var member = type_members[i];
3824
3825                                                         //
3826                                                         // Methods in a base class are not candidates if any method in a derived
3827                                                         // class is applicable
3828                                                         //
3829                                                         if ((member.Modifiers & Modifiers.OVERRIDE) != 0)
3830                                                                 continue;
3831
3832                                                         if (!member.IsAccessible (current_type) && !error_mode)
3833                                                                 continue;
3834
3835                                                         if (!(member is IParametersMember)) {
3836                                                                 //
3837                                                                 // Will use it later to report ambiguity between best method and invocable member
3838                                                                 //
3839                                                                 if (Invocation.IsMemberInvocable (member))
3840                                                                         invocable_member = member;
3841
3842                                                                 continue;
3843                                                         }
3844
3845                                                         //
3846                                                         // Check if candidate is applicable
3847                                                         //
3848                                                         bool params_expanded_form = false;
3849                                                         int candidate_rate = IsApplicable (rc, ref candidate_args, args_count, ref member, ref params_expanded_form);
3850
3851                                                         //
3852                                                         // How does it score compare to others
3853                                                         //
3854                                                         if (candidate_rate < best_candidate_rate) {
3855                                                                 best_candidate_rate = candidate_rate;
3856                                                                 best_candidate = member;
3857                                                                 best_candidate_args = candidate_args;
3858                                                                 best_candidate_params = params_expanded_form;
3859                                                         } else if (candidate_rate == 0) {
3860                                                                 // Is new candidate better
3861                                                                 if (BetterFunction (rc, candidate_args, member, params_expanded_form, best_candidate, best_candidate_params)) {
3862                                                                         best_candidate = member;
3863                                                                         best_candidate_args = candidate_args;
3864                                                                         best_candidate_params = params_expanded_form;
3865                                                                 } else {
3866                                                                         // It's not better but any other found later could be but we are not sure yet
3867                                                                         if (ambiguous_candidates == null)
3868                                                                                 ambiguous_candidates = new List<AmbiguousCandidate> ();
3869
3870                                                                         ambiguous_candidates.Add (new AmbiguousCandidate (member, params_expanded_form));
3871                                                                 }
3872                                                         }
3873
3874                                                         // Restore expanded arguments
3875                                                         if (candidate_args != args)
3876                                                                 candidate_args = args;
3877                                                 }
3878                                         } while (best_candidate_rate != 0 && (type_members = base_provider.GetBaseMembers (type_members[0].DeclaringType.BaseType)) != null);
3879                                 } finally {
3880                                         if (prev_recorder != null)
3881                                                 rc.Report.SetPrinter (prev_recorder);
3882                                 }
3883
3884                                 //
3885                                 // We've found exact match
3886                                 //
3887                                 if (best_candidate_rate == 0)
3888                                         break;
3889
3890                                 //
3891                                 // Try extension methods lookup when no ordinary method match was found and provider enables it
3892                                 //
3893                                 if (!error_mode) {
3894                                         var emg = base_provider.LookupExtensionMethod (rc);
3895                                         if (emg != null) {
3896                                                 emg = emg.OverloadResolve (rc, ref args, null, restrictions);
3897                                                 if (emg != null) {
3898                                                         best_candidate_extension_group = emg;
3899                                                         return (T) (MemberSpec) emg.BestCandidate;
3900                                                 }
3901                                         }
3902                                 }
3903
3904                                 // Don't run expensive error reporting mode for probing
3905                                 if (IsProbingOnly)
3906                                         return null;
3907
3908                                 if (error_mode)
3909                                         break;
3910
3911                                 lambda_conv_msgs = null;
3912                                 error_mode = true;
3913                         }
3914
3915                         //
3916                         // No best member match found, report an error
3917                         //
3918                         if (best_candidate_rate != 0 || error_mode) {
3919                                 ReportOverloadError (rc, best_candidate, best_candidate_args, best_candidate_params);
3920                                 return null;
3921                         }
3922
3923                         // TODO: quite slow
3924                         if (args_count != 0 && args.HasDynamic) {
3925                                 if (args [0].ArgType == Argument.AType.ExtensionType) {
3926                                         rc.Report.Error (1973, loc,
3927                                                 "Type `{0}' does not contain a member `{1}' and the best extension method overload `{2}' cannot be dynamically dispatched. Consider calling the method without the extension method syntax",
3928                                                 args [0].Type.GetSignatureForError (), best_candidate.Name, best_candidate.GetSignatureForError());
3929                                 }
3930
3931                                 BestCandidateIsDynamic = true;
3932                                 return null;
3933                         }
3934
3935                         if (ambiguous_candidates != null) {
3936                                 //
3937                                 // Now check that there are no ambiguities i.e the selected method
3938                                 // should be better than all the others
3939                                 //
3940                                 for (int ix = 0; ix < ambiguous_candidates.Count; ix++) {
3941                                         var candidate = ambiguous_candidates [ix];
3942
3943                                         if (!BetterFunction (rc, candidate_args, best_candidate, best_candidate_params, candidate.Member, candidate.Expanded)) {
3944                                                 var ambiguous = candidate.Member;
3945                                                 if (custom_errors == null || !custom_errors.AmbiguousCandidates (rc, best_candidate, ambiguous)) {
3946                                                         rc.Report.SymbolRelatedToPreviousError (best_candidate);
3947                                                         rc.Report.SymbolRelatedToPreviousError (ambiguous);
3948                                                         rc.Report.Error (121, loc, "The call is ambiguous between the following methods or properties: `{0}' and `{1}'",
3949                                                                 best_candidate.GetSignatureForError (), ambiguous.GetSignatureForError ());
3950                                                 }
3951
3952                                                 return (T) best_candidate;
3953                                         }
3954                                 }
3955                         }
3956
3957                         if (invocable_member != null) {
3958                                 rc.Report.SymbolRelatedToPreviousError (best_candidate);
3959                                 rc.Report.SymbolRelatedToPreviousError (invocable_member);
3960                                 rc.Report.Warning (467, 2, loc, "Ambiguity between method `{0}' and invocable non-method `{1}'. Using method group",
3961                                         best_candidate.GetSignatureForError (), invocable_member.GetSignatureForError ());
3962                         }
3963
3964                         //
3965                         // And now check if the arguments are all
3966                         // compatible, perform conversions if
3967                         // necessary etc. and return if everything is
3968                         // all right
3969                         //
3970                         if (!VerifyArguments (rc, ref best_candidate_args, best_candidate, best_candidate_params))
3971                                 return null;
3972
3973                         if (best_candidate == null)
3974                                 return null;
3975
3976                         //
3977                         // Check ObsoleteAttribute on the best method
3978                         //
3979                         ObsoleteAttribute oa = best_candidate.GetAttributeObsolete ();
3980                         if (oa != null && !rc.IsObsolete)
3981                                 AttributeTester.Report_ObsoleteMessage (oa, best_candidate.GetSignatureForError (), loc, rc.Report);
3982
3983                         best_candidate.MemberDefinition.SetIsUsed ();
3984
3985                         args = best_candidate_args;
3986                         return (T) best_candidate;
3987                 }
3988
3989                 public MethodSpec ResolveOperator (ResolveContext rc, ref Arguments args)
3990                 {
3991                         return ResolveMember<MethodSpec> (rc, ref args);
3992                 }
3993
3994                 void ReportArgumentMismatch (ResolveContext ec, int idx, MemberSpec method,
3995                                                                                                         Argument a, AParametersCollection expected_par, TypeSpec paramType)
3996                 {
3997                         if (custom_errors != null && custom_errors.ArgumentMismatch (ec, method, a, idx))
3998                                 return;
3999
4000                         if (a is CollectionElementInitializer.ElementInitializerArgument) {
4001                                 ec.Report.SymbolRelatedToPreviousError (method);
4002                                 if ((expected_par.FixedParameters[idx].ModFlags & Parameter.Modifier.ISBYREF) != 0) {
4003                                         ec.Report.Error (1954, loc, "The best overloaded collection initalizer method `{0}' cannot have 'ref', or `out' modifier",
4004                                                 TypeManager.CSharpSignature (method));
4005                                         return;
4006                                 }
4007                                 ec.Report.Error (1950, loc, "The best overloaded collection initalizer method `{0}' has some invalid arguments",
4008                                           TypeManager.CSharpSignature (method));
4009                         } else if (IsDelegateInvoke) {
4010                                 ec.Report.Error (1594, loc, "Delegate `{0}' has some invalid arguments",
4011                                         DelegateType.GetSignatureForError ());
4012                         } else {
4013                                 ec.Report.SymbolRelatedToPreviousError (method);
4014                                 ec.Report.Error (1502, loc, "The best overloaded method match for `{0}' has some invalid arguments",
4015                                         method.GetSignatureForError ());
4016                         }
4017
4018                         Parameter.Modifier mod = idx >= expected_par.Count ? 0 : expected_par.FixedParameters[idx].ModFlags;
4019
4020                         string index = (idx + 1).ToString ();
4021                         if (((mod & (Parameter.Modifier.REF | Parameter.Modifier.OUT)) ^
4022                                 (a.Modifier & (Parameter.Modifier.REF | Parameter.Modifier.OUT))) != 0) {
4023                                 if ((mod & Parameter.Modifier.ISBYREF) == 0)
4024                                         ec.Report.Error (1615, loc, "Argument `#{0}' does not require `{1}' modifier. Consider removing `{1}' modifier",
4025                                                 index, Parameter.GetModifierSignature (a.Modifier));
4026                                 else
4027                                         ec.Report.Error (1620, loc, "Argument `#{0}' is missing `{1}' modifier",
4028                                                 index, Parameter.GetModifierSignature (mod));
4029                         } else {
4030                                 string p1 = a.GetSignatureForError ();
4031                                 string p2 = TypeManager.CSharpName (paramType);
4032
4033                                 if (p1 == p2) {
4034                                         ec.Report.ExtraInformation (loc, "(equally named types possibly from different assemblies in previous ");
4035                                         ec.Report.SymbolRelatedToPreviousError (a.Expr.Type);
4036                                         ec.Report.SymbolRelatedToPreviousError (paramType);
4037                                 }
4038
4039                                 ec.Report.Error (1503, loc,
4040                                         "Argument `#{0}' cannot convert `{1}' expression to type `{2}'", index, p1, p2);
4041                         }
4042                 }
4043
4044                 //
4045                 // We have failed to find exact match so we return error info about the closest match
4046                 //
4047                 void ReportOverloadError (ResolveContext rc, MemberSpec best_candidate, Arguments args, bool params_expanded)
4048                 {
4049                         int ta_count = type_arguments == null ? 0 : type_arguments.Count;
4050                         int arg_count = args == null ? 0 : args.Count;
4051
4052                         if (ta_count != best_candidate.Arity && (ta_count > 0 || ((IParametersMember) best_candidate).Parameters.IsEmpty)) {
4053                                 var mg = new MethodGroupExpr (new [] { best_candidate }, best_candidate.DeclaringType, loc);
4054                                 mg.Error_TypeArgumentsCannotBeUsed (rc.Report, loc, best_candidate, ta_count);
4055                                 return;
4056                         }
4057
4058                         if (lambda_conv_msgs != null) {
4059                                 if (lambda_conv_msgs.Merge (rc.Report.Printer))
4060                                         return;
4061                         }
4062
4063                         //
4064                         // For candidates which match on parameters count report more details about incorrect arguments
4065                         //
4066                         var pm = best_candidate as IParametersMember;
4067                         if (pm != null) {
4068                                 int unexpanded_count = pm.Parameters.HasParams ? pm.Parameters.Count - 1 : pm.Parameters.Count;
4069                                 if (pm.Parameters.Count == arg_count || params_expanded || unexpanded_count == arg_count) {
4070                                         // Reject any inaccessible member
4071                                         if (!best_candidate.IsAccessible (rc.CurrentType)) {
4072                                                 rc.Report.SymbolRelatedToPreviousError (best_candidate);
4073                                                 Expression.ErrorIsInaccesible (rc, best_candidate.GetSignatureForError (), loc);
4074                                                 return;
4075                                         }
4076
4077                                         var ms = best_candidate as MethodSpec;
4078                                         if (ms != null && ms.IsGeneric && ta_count == 0) {
4079                                                 if (custom_errors != null && custom_errors.TypeInferenceFailed (rc, best_candidate))
4080                                                         return;
4081
4082                                                 rc.Report.Error (411, loc,
4083                                                         "The type arguments for method `{0}' cannot be inferred from the usage. Try specifying the type arguments explicitly",
4084                                                         ms.GetGenericMethodDefinition ().GetSignatureForError ());
4085                                                 return;
4086                                         }
4087
4088                                         VerifyArguments (rc, ref args, best_candidate, params_expanded);
4089                                         return;
4090                                 }
4091                         }
4092
4093                         //
4094                         // We failed to find any method with correct argument count, report best candidate
4095                         //
4096                         if (custom_errors != null && custom_errors.NoArgumentMatch (rc, best_candidate))
4097                                 return;
4098
4099                         if (best_candidate.Kind == MemberKind.Constructor) {
4100                                 rc.Report.SymbolRelatedToPreviousError (best_candidate);
4101                                 Error_ConstructorMismatch (rc, best_candidate.DeclaringType, arg_count, loc);
4102                         } else if (IsDelegateInvoke) {
4103                                 rc.Report.SymbolRelatedToPreviousError (DelegateType);
4104                                 rc.Report.Error (1593, loc, "Delegate `{0}' does not take `{1}' arguments",
4105                                         DelegateType.GetSignatureForError (), arg_count.ToString ());
4106                         } else {
4107                                 string name = best_candidate.Kind == MemberKind.Indexer ? "this" : best_candidate.Name;
4108                                 rc.Report.SymbolRelatedToPreviousError (best_candidate);
4109                                 rc.Report.Error (1501, loc, "No overload for method `{0}' takes `{1}' arguments",
4110                                         name, arg_count.ToString ());
4111                         }
4112                 }
4113
4114                 bool VerifyArguments (ResolveContext ec, ref Arguments args, MemberSpec member, bool chose_params_expanded)
4115                 {
4116                         var pm = member as IParametersMember;
4117                         var pd = pm.Parameters;
4118
4119                         Parameter.Modifier p_mod = 0;
4120                         TypeSpec pt = null;
4121                         int a_idx = 0, a_pos = 0;
4122                         Argument a = null;
4123                         ArrayInitializer params_initializers = null;
4124                         bool has_unsafe_arg = pm.MemberType.IsPointer;
4125                         int arg_count = args == null ? 0 : args.Count;
4126
4127                         for (; a_idx < arg_count; a_idx++, ++a_pos) {
4128                                 a = args[a_idx];
4129                                 if (p_mod != Parameter.Modifier.PARAMS) {
4130                                         p_mod = pd.FixedParameters[a_idx].ModFlags;
4131                                         pt = pd.Types[a_idx];
4132                                         has_unsafe_arg |= pt.IsPointer;
4133
4134                                         if (p_mod == Parameter.Modifier.PARAMS) {
4135                                                 if (chose_params_expanded) {
4136                                                         params_initializers = new ArrayInitializer (arg_count - a_idx, a.Expr.Location);
4137                                                         pt = TypeManager.GetElementType (pt);
4138                                                 }
4139                                         }
4140                                 }
4141
4142                                 //
4143                                 // Types have to be identical when ref or out modifer is used
4144                                 //
4145                                 if (a.Modifier != 0 || (p_mod & ~Parameter.Modifier.PARAMS) != 0) {
4146                                         if ((p_mod & ~Parameter.Modifier.PARAMS) != a.Modifier)
4147                                                 break;
4148
4149                                         if (a.Expr.Type == pt || TypeSpecComparer.IsEqual (a.Expr.Type, pt))
4150                                                 continue;
4151
4152                                         break;
4153                                 }
4154
4155                                 NamedArgument na = a as NamedArgument;
4156                                 if (na != null) {
4157                                         int name_index = pd.GetParameterIndexByName (na.Name);
4158                                         if (name_index < 0 || name_index >= pd.Count) {
4159                                                 if (IsDelegateInvoke) {
4160                                                         ec.Report.SymbolRelatedToPreviousError (DelegateType);
4161                                                         ec.Report.Error (1746, na.Location,
4162                                                                 "The delegate `{0}' does not contain a parameter named `{1}'",
4163                                                                 DelegateType.GetSignatureForError (), na.Name);
4164                                                 } else {
4165                                                         ec.Report.SymbolRelatedToPreviousError (member);
4166                                                         ec.Report.Error (1739, na.Location,
4167                                                                 "The best overloaded method match for `{0}' does not contain a parameter named `{1}'",
4168                                                                 TypeManager.CSharpSignature (member), na.Name);
4169                                                 }
4170                                         } else if (args[name_index] != a) {
4171                                                 if (IsDelegateInvoke)
4172                                                         ec.Report.SymbolRelatedToPreviousError (DelegateType);
4173                                                 else
4174                                                         ec.Report.SymbolRelatedToPreviousError (member);
4175
4176                                                 ec.Report.Error (1744, na.Location,
4177                                                         "Named argument `{0}' cannot be used for a parameter which has positional argument specified",
4178                                                         na.Name);
4179                                         }
4180                                 }
4181
4182                                 if (a.Expr.Type == InternalType.Dynamic)
4183                                         continue;
4184
4185                                 if ((restrictions & Restrictions.Covariant) != 0 && !Delegate.IsTypeCovariant (a.Expr, pt)) {
4186                                         custom_errors.NoArgumentMatch (ec, member);
4187                                         return false;
4188                                 }
4189
4190                                 Expression conv = Convert.ImplicitConversion (ec, a.Expr, pt, loc);
4191                                 if (conv == null)
4192                                         break;
4193
4194                                 //
4195                                 // Convert params arguments to an array initializer
4196                                 //
4197                                 if (params_initializers != null) {
4198                                         // we choose to use 'a.Expr' rather than 'conv' so that
4199                                         // we don't hide the kind of expression we have (esp. CompoundAssign.Helper)
4200                                         params_initializers.Add (a.Expr);
4201                                         args.RemoveAt (a_idx--);
4202                                         --arg_count;
4203                                         continue;
4204                                 }
4205
4206                                 // Update the argument with the implicit conversion
4207                                 a.Expr = conv;
4208                         }
4209
4210                         if (a_idx != arg_count) {
4211                                 ReportArgumentMismatch (ec, a_pos, member, a, pd, pt);
4212                                 return false;
4213                         }
4214
4215                         //
4216                         // Fill not provided arguments required by params modifier
4217                         //
4218                         if (params_initializers == null && pd.HasParams && arg_count + 1 == pd.Count) {
4219                                 if (args == null)
4220                                         args = new Arguments (1);
4221
4222                                 pt = pd.Types[pd.Count - 1];
4223                                 pt = TypeManager.GetElementType (pt);
4224                                 has_unsafe_arg |= pt.IsPointer;
4225                                 params_initializers = new ArrayInitializer (0, loc);
4226                         }
4227
4228                         //
4229                         // Append an array argument with all params arguments
4230                         //
4231                         if (params_initializers != null) {
4232                                 args.Add (new Argument (
4233                                         new ArrayCreation (new TypeExpression (pt, loc), params_initializers, loc).Resolve (ec)));
4234                                 arg_count++;
4235                         }
4236
4237                         if (has_unsafe_arg && !ec.IsUnsafe) {
4238                                 Expression.UnsafeError (ec, loc);
4239                         }
4240
4241                         return true;
4242                 }
4243         }
4244
4245         public class ConstantExpr : MemberExpr
4246         {
4247                 ConstSpec constant;
4248
4249                 public ConstantExpr (ConstSpec constant, Location loc)
4250                 {
4251                         this.constant = constant;
4252                         this.loc = loc;
4253                 }
4254
4255                 public override string Name {
4256                         get { throw new NotImplementedException (); }
4257                 }
4258
4259                 public override bool IsInstance {
4260                         get { return !IsStatic; }
4261                 }
4262
4263                 public override bool IsStatic {
4264                         get { return true; }
4265                 }
4266
4267                 protected override TypeSpec DeclaringType {
4268                         get { return constant.DeclaringType; }
4269                 }
4270
4271                 public override Expression CreateExpressionTree (ResolveContext ec)
4272                 {
4273                         throw new NotSupportedException ("ET");
4274                 }
4275
4276                 protected override Expression DoResolve (ResolveContext rc)
4277                 {
4278                         ResolveInstanceExpression (rc);
4279                         DoBestMemberChecks (rc, constant);
4280
4281                         var c = constant.GetConstant (rc);
4282
4283                         // Creates reference expression to the constant value
4284                         return Constant.CreateConstant (rc, constant.MemberType, c.GetValue (), loc);
4285                 }
4286
4287                 public override void Emit (EmitContext ec)
4288                 {
4289                         throw new NotSupportedException ();
4290                 }
4291
4292                 public override string GetSignatureForError ()
4293                 {
4294                         return constant.GetSignatureForError ();
4295                 }
4296
4297                 public override void SetTypeArguments (ResolveContext ec, TypeArguments ta)
4298                 {
4299                         Error_TypeArgumentsCannotBeUsed (ec.Report, "constant", GetSignatureForError (), loc);
4300                 }
4301         }
4302
4303         /// <summary>
4304         ///   Fully resolved expression that evaluates to a Field
4305         /// </summary>
4306         public class FieldExpr : MemberExpr, IDynamicAssign, IMemoryLocation, IVariableReference {
4307                 protected FieldSpec spec;
4308                 VariableInfo variable_info;
4309
4310                 LocalTemporary temp;
4311                 bool prepared;
4312
4313                 protected FieldExpr (Location l)
4314                 {
4315                         loc = l;
4316                 }
4317
4318                 public FieldExpr (FieldSpec spec, Location loc)
4319                 {
4320                         this.spec = spec;
4321                         this.loc = loc;
4322
4323                         type = spec.MemberType;
4324                 }
4325
4326                 public FieldExpr (FieldBase fi, Location l)
4327                         : this (fi.Spec, l)
4328                 {
4329                 }
4330
4331 #region Properties
4332
4333                 public override string Name {
4334                         get {
4335                                 return spec.Name;
4336                         }
4337                 }
4338
4339                 public bool IsHoisted {
4340                         get {
4341                                 IVariableReference hv = InstanceExpression as IVariableReference;
4342                                 return hv != null && hv.IsHoisted;
4343                         }
4344                 }
4345
4346                 public override bool IsInstance {
4347                         get {
4348                                 return !spec.IsStatic;
4349                         }
4350                 }
4351
4352                 public override bool IsStatic {
4353                         get {
4354                                 return spec.IsStatic;
4355                         }
4356                 }
4357
4358                 public FieldSpec Spec {
4359                         get {
4360                                 return spec;
4361                         }
4362                 }
4363
4364                 protected override TypeSpec DeclaringType {
4365                         get {
4366                                 return spec.DeclaringType;
4367                         }
4368                 }
4369
4370                 public VariableInfo VariableInfo {
4371                         get {
4372                                 return variable_info;
4373                         }
4374                 }
4375
4376 #endregion
4377
4378                 public override string GetSignatureForError ()
4379                 {
4380                         return TypeManager.GetFullNameSignature (spec);
4381                 }
4382
4383                 public bool IsMarshalByRefAccess ()
4384                 {
4385                         // Checks possible ldflda of field access expression
4386                         return !spec.IsStatic && TypeManager.IsValueType (spec.MemberType) &&
4387                                 TypeSpec.IsBaseClass (spec.DeclaringType, TypeManager.mbr_type, false) &&
4388                                 !(InstanceExpression is This);
4389                 }
4390
4391                 public void SetHasAddressTaken ()
4392                 {
4393                         IVariableReference vr = InstanceExpression as IVariableReference;
4394                         if (vr != null)
4395                                 vr.SetHasAddressTaken ();
4396                 }
4397
4398                 public override Expression CreateExpressionTree (ResolveContext ec)
4399                 {
4400                         Expression instance;
4401                         if (InstanceExpression == null) {
4402                                 instance = new NullLiteral (loc);
4403                         } else {
4404                                 instance = InstanceExpression.CreateExpressionTree (ec);
4405                         }
4406
4407                         Arguments args = Arguments.CreateForExpressionTree (ec, null,
4408                                 instance,
4409                                 CreateTypeOfExpression ());
4410
4411                         return CreateExpressionFactoryCall (ec, "Field", args);
4412                 }
4413
4414                 public Expression CreateTypeOfExpression ()
4415                 {
4416                         return new TypeOfField (spec, loc);
4417                 }
4418
4419                 protected override Expression DoResolve (ResolveContext ec)
4420                 {
4421                         return DoResolve (ec, false, false);
4422                 }
4423
4424                 Expression DoResolve (ResolveContext ec, bool lvalue_instance, bool out_access)
4425                 {
4426                         if (ResolveInstanceExpression (ec)) {
4427                                 // Resolve the field's instance expression while flow analysis is turned
4428                                 // off: when accessing a field "a.b", we must check whether the field
4429                                 // "a.b" is initialized, not whether the whole struct "a" is initialized.
4430
4431                                 if (lvalue_instance) {
4432                                         using (ec.With (ResolveContext.Options.DoFlowAnalysis, false)) {
4433                                                 Expression right_side =
4434                                                         out_access ? EmptyExpression.LValueMemberOutAccess : EmptyExpression.LValueMemberAccess;
4435
4436                                                 InstanceExpression = InstanceExpression.ResolveLValue (ec, right_side);
4437                                         }
4438                                 } else {
4439                                         using (ec.With (ResolveContext.Options.DoFlowAnalysis, false)) {
4440                                                 InstanceExpression = InstanceExpression.Resolve (ec, ResolveFlags.VariableOrValue);
4441                                         }
4442                                 }
4443
4444                                 if (InstanceExpression == null)
4445                                         return null;
4446
4447                                 using (ec.Set (ResolveContext.Options.OmitStructFlowAnalysis)) {
4448                                         InstanceExpression.CheckMarshalByRefAccess (ec);
4449                                 }
4450                         }
4451
4452                         DoBestMemberChecks (ec, spec);
4453
4454                         var fb = spec as FixedFieldSpec;
4455                         IVariableReference var = InstanceExpression as IVariableReference;
4456
4457                         if (lvalue_instance && var != null && var.VariableInfo != null) {
4458                                 var.VariableInfo.SetFieldAssigned (ec, Name);
4459                         }
4460
4461                         if (fb != null) {
4462                                 IFixedExpression fe = InstanceExpression as IFixedExpression;
4463                                 if (!ec.HasSet (ResolveContext.Options.FixedInitializerScope) && (fe == null || !fe.IsFixed)) {
4464                                         ec.Report.Error (1666, loc, "You cannot use fixed size buffers contained in unfixed expressions. Try using the fixed statement");
4465                                 }
4466
4467                                 if (InstanceExpression.eclass != ExprClass.Variable) {
4468                                         ec.Report.SymbolRelatedToPreviousError (spec);
4469                                         ec.Report.Error (1708, loc, "`{0}': Fixed size buffers can only be accessed through locals or fields",
4470                                                 TypeManager.GetFullNameSignature (spec));
4471                                 } else if (var != null && var.IsHoisted) {
4472                                         AnonymousMethodExpression.Error_AddressOfCapturedVar (ec, var, loc);
4473                                 }
4474
4475                                 return new FixedBufferPtr (this, fb.ElementType, loc).Resolve (ec);
4476                         }
4477
4478                         eclass = ExprClass.Variable;
4479
4480                         // If the instance expression is a local variable or parameter.
4481                         if (var == null || var.VariableInfo == null)
4482                                 return this;
4483
4484                         VariableInfo vi = var.VariableInfo;
4485                         if (!vi.IsFieldAssigned (ec, Name, loc))
4486                                 return null;
4487
4488                         variable_info = vi.GetSubStruct (Name);
4489                         return this;
4490                 }
4491
4492                 static readonly int [] codes = {
4493                         191,    // instance, write access
4494                         192,    // instance, out access
4495                         198,    // static, write access
4496                         199,    // static, out access
4497                         1648,   // member of value instance, write access
4498                         1649,   // member of value instance, out access
4499                         1650,   // member of value static, write access
4500                         1651    // member of value static, out access
4501                 };
4502
4503                 static readonly string [] msgs = {
4504                         /*0191*/ "A readonly field `{0}' cannot be assigned to (except in a constructor or a variable initializer)",
4505                         /*0192*/ "A readonly field `{0}' cannot be passed ref or out (except in a constructor)",
4506                         /*0198*/ "A static readonly field `{0}' cannot be assigned to (except in a static constructor or a variable initializer)",
4507                         /*0199*/ "A static readonly field `{0}' cannot be passed ref or out (except in a static constructor)",
4508                         /*1648*/ "Members of readonly field `{0}' cannot be modified (except in a constructor or a variable initializer)",
4509                         /*1649*/ "Members of readonly field `{0}' cannot be passed ref or out (except in a constructor)",
4510                         /*1650*/ "Fields of static readonly field `{0}' cannot be assigned to (except in a static constructor or a variable initializer)",
4511                         /*1651*/ "Fields of static readonly field `{0}' cannot be passed ref or out (except in a static constructor)"
4512                 };
4513
4514                 // The return value is always null.  Returning a value simplifies calling code.
4515                 Expression Report_AssignToReadonly (ResolveContext ec, Expression right_side)
4516                 {
4517                         int i = 0;
4518                         if (right_side == EmptyExpression.OutAccess.Instance || right_side == EmptyExpression.LValueMemberOutAccess)
4519                                 i += 1;
4520                         if (IsStatic)
4521                                 i += 2;
4522                         if (right_side == EmptyExpression.LValueMemberAccess || right_side == EmptyExpression.LValueMemberOutAccess)
4523                                 i += 4;
4524                         ec.Report.Error (codes [i], loc, msgs [i], GetSignatureForError ());
4525
4526                         return null;
4527                 }
4528
4529                 override public Expression DoResolveLValue (ResolveContext ec, Expression right_side)
4530                 {
4531                         bool lvalue_instance = IsInstance && spec.DeclaringType.IsStruct;
4532                         bool out_access = right_side == EmptyExpression.OutAccess.Instance || right_side == EmptyExpression.LValueMemberOutAccess;
4533
4534                         Expression e = DoResolve (ec, lvalue_instance, out_access);
4535
4536                         if (e == null)
4537                                 return null;
4538
4539                         spec.MemberDefinition.SetIsAssigned ();
4540
4541                         if ((right_side == EmptyExpression.UnaryAddress || right_side == EmptyExpression.OutAccess.Instance) &&
4542                                         (spec.Modifiers & Modifiers.VOLATILE) != 0) {
4543                                 ec.Report.Warning (420, 1, loc,
4544                                         "`{0}': A volatile field references will not be treated as volatile",
4545                                         spec.GetSignatureForError ());
4546                         }
4547
4548                         if (spec.IsReadOnly) {
4549                                 // InitOnly fields can only be assigned in constructors or initializers
4550                                 if (!ec.HasAny (ResolveContext.Options.FieldInitializerScope | ResolveContext.Options.ConstructorScope))
4551                                         return Report_AssignToReadonly (ec, right_side);
4552
4553                                 if (ec.HasSet (ResolveContext.Options.ConstructorScope)) {
4554
4555                                         // InitOnly fields cannot be assigned-to in a different constructor from their declaring type
4556                                         if (ec.CurrentMemberDefinition.Parent.Definition != spec.DeclaringType.GetDefinition ())
4557                                                 return Report_AssignToReadonly (ec, right_side);
4558                                         // static InitOnly fields cannot be assigned-to in an instance constructor
4559                                         if (IsStatic && !ec.IsStatic)
4560                                                 return Report_AssignToReadonly (ec, right_side);
4561                                         // instance constructors can't modify InitOnly fields of other instances of the same type
4562                                         if (!IsStatic && !(InstanceExpression is This))
4563                                                 return Report_AssignToReadonly (ec, right_side);
4564                                 }
4565                         }
4566
4567                         if (right_side == EmptyExpression.OutAccess.Instance &&
4568                                 !IsStatic && !(InstanceExpression is This) && TypeManager.mbr_type != null && TypeSpec.IsBaseClass (spec.DeclaringType, TypeManager.mbr_type, false)) {
4569                                 ec.Report.SymbolRelatedToPreviousError (spec.DeclaringType);
4570                                 ec.Report.Warning (197, 1, loc,
4571                                                 "Passing `{0}' as ref or out or taking its address may cause a runtime exception because it is a field of a marshal-by-reference class",
4572                                                 GetSignatureForError ());
4573                         }
4574
4575                         eclass = ExprClass.Variable;
4576                         return this;
4577                 }
4578
4579                 public override int GetHashCode ()
4580                 {
4581                         return spec.GetHashCode ();
4582                 }
4583
4584                 public bool IsFixed {
4585                         get {
4586                                 //
4587                                 // A variable of the form V.I is fixed when V is a fixed variable of a struct type
4588                                 //
4589                                 IVariableReference variable = InstanceExpression as IVariableReference;
4590                                 if (variable != null)
4591                                         return InstanceExpression.Type.IsStruct && variable.IsFixed;
4592
4593                                 IFixedExpression fe = InstanceExpression as IFixedExpression;
4594                                 return fe != null && fe.IsFixed;
4595                         }
4596                 }
4597
4598                 public override bool Equals (object obj)
4599                 {
4600                         FieldExpr fe = obj as FieldExpr;
4601                         if (fe == null)
4602                                 return false;
4603
4604                         if (spec != fe.spec)
4605                                 return false;
4606
4607                         if (InstanceExpression == null || fe.InstanceExpression == null)
4608                                 return true;
4609
4610                         return InstanceExpression.Equals (fe.InstanceExpression);
4611                 }
4612
4613                 public void Emit (EmitContext ec, bool leave_copy)
4614                 {
4615                         bool is_volatile = false;
4616
4617                         if ((spec.Modifiers & Modifiers.VOLATILE) != 0)
4618                                 is_volatile = true;
4619
4620                         spec.MemberDefinition.SetIsUsed ();
4621
4622                         if (IsStatic){
4623                                 if (is_volatile)
4624                                         ec.Emit (OpCodes.Volatile);
4625
4626                                 ec.Emit (OpCodes.Ldsfld, spec);
4627                         } else {
4628                                 if (!prepared)
4629                                         EmitInstance (ec, false);
4630
4631                                 // Optimization for build-in types
4632                                 if (TypeManager.IsStruct (type) && type == ec.MemberContext.CurrentType && InstanceExpression.Type == type) {
4633                                         ec.EmitLoadFromPtr (type);
4634                                 } else {
4635                                         var ff = spec as FixedFieldSpec;
4636                                         if (ff != null) {
4637                                                 ec.Emit (OpCodes.Ldflda, spec);
4638                                                 ec.Emit (OpCodes.Ldflda, ff.Element);
4639                                         } else {
4640                                                 if (is_volatile)
4641                                                         ec.Emit (OpCodes.Volatile);
4642
4643                                                 ec.Emit (OpCodes.Ldfld, spec);
4644                                         }
4645                                 }
4646                         }
4647
4648                         if (leave_copy) {
4649                                 ec.Emit (OpCodes.Dup);
4650                                 if (!IsStatic) {
4651                                         temp = new LocalTemporary (this.Type);
4652                                         temp.Store (ec);
4653                                 }
4654                         }
4655                 }
4656
4657                 public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool prepare_for_load)
4658                 {
4659                         prepared = prepare_for_load;
4660                         if (IsInstance)
4661                                 EmitInstance (ec, prepared);
4662
4663                         source.Emit (ec);
4664                         if (leave_copy) {
4665                                 ec.Emit (OpCodes.Dup);
4666                                 if (!IsStatic) {
4667                                         temp = new LocalTemporary (this.Type);
4668                                         temp.Store (ec);
4669                                 }
4670                         }
4671
4672                         if ((spec.Modifiers & Modifiers.VOLATILE) != 0)
4673                                 ec.Emit (OpCodes.Volatile);
4674
4675                         spec.MemberDefinition.SetIsAssigned ();
4676
4677                         if (IsStatic)
4678                                 ec.Emit (OpCodes.Stsfld, spec);
4679                         else
4680                                 ec.Emit (OpCodes.Stfld, spec);
4681
4682                         if (temp != null) {
4683                                 temp.Emit (ec);
4684                                 temp.Release (ec);
4685                                 temp = null;
4686                         }
4687                 }
4688
4689                 public override void Emit (EmitContext ec)
4690                 {
4691                         Emit (ec, false);
4692                 }
4693
4694                 public override void EmitSideEffect (EmitContext ec)
4695                 {
4696                         bool is_volatile = (spec.Modifiers & Modifiers.VOLATILE) != 0;
4697
4698                         if (is_volatile) // || is_marshal_by_ref ())
4699                                 base.EmitSideEffect (ec);
4700                 }
4701
4702                 public override void Error_VariableIsUsedBeforeItIsDeclared (Report r, string name)
4703                 {
4704                         r.Error (844, loc,
4705                                 "A local variable `{0}' cannot be used before it is declared. Consider renaming the local variable when it hides the field `{1}'",
4706                                 name, GetSignatureForError ());
4707                 }
4708
4709                 public void AddressOf (EmitContext ec, AddressOp mode)
4710                 {
4711                         if ((mode & AddressOp.Store) != 0)
4712                                 spec.MemberDefinition.SetIsAssigned ();
4713                         if ((mode & AddressOp.Load) != 0)
4714                                 spec.MemberDefinition.SetIsUsed ();
4715
4716                         //
4717                         // Handle initonly fields specially: make a copy and then
4718                         // get the address of the copy.
4719                         //
4720                         bool need_copy;
4721                         if (spec.IsReadOnly){
4722                                 need_copy = true;
4723                                 if (ec.HasSet (EmitContext.Options.ConstructorScope)){
4724                                         if (IsStatic){
4725                                                 if (ec.IsStatic)
4726                                                         need_copy = false;
4727                                         } else
4728                                                 need_copy = false;
4729                                 }
4730                         } else
4731                                 need_copy = false;
4732
4733                         if (need_copy){
4734                                 LocalBuilder local;
4735                                 Emit (ec);
4736                                 local = ec.DeclareLocal (type, false);
4737                                 ec.Emit (OpCodes.Stloc, local);
4738                                 ec.Emit (OpCodes.Ldloca, local);
4739                                 return;
4740                         }
4741
4742
4743                         if (IsStatic){
4744                                 ec.Emit (OpCodes.Ldsflda, spec);
4745                         } else {
4746                                 if (!prepared)
4747                                         EmitInstance (ec, false);
4748                                 ec.Emit (OpCodes.Ldflda, spec);
4749                         }
4750                 }
4751
4752                 public SLE.Expression MakeAssignExpression (BuilderContext ctx, Expression source)
4753                 {
4754                         return MakeExpression (ctx);
4755                 }
4756
4757                 public override SLE.Expression MakeExpression (BuilderContext ctx)
4758                 {
4759                         return SLE.Expression.Field (InstanceExpression.MakeExpression (ctx), spec.GetMetaInfo ());
4760                 }
4761
4762                 public override void SetTypeArguments (ResolveContext ec, TypeArguments ta)
4763                 {
4764                         Error_TypeArgumentsCannotBeUsed (ec.Report, "field", GetSignatureForError (), loc);
4765                 }
4766         }
4767
4768
4769         /// <summary>
4770         ///   Expression that evaluates to a Property.  The Assign class
4771         ///   might set the `Value' expression if we are in an assignment.
4772         ///
4773         ///   This is not an LValue because we need to re-write the expression, we
4774         ///   can not take data from the stack and store it.
4775         /// </summary>
4776         class PropertyExpr : PropertyOrIndexerExpr<PropertySpec>
4777         {
4778                 public PropertyExpr (PropertySpec spec, Location l)
4779                         : base (l)
4780                 {
4781                         best_candidate = spec;
4782                         type = spec.MemberType;
4783                 }
4784
4785                 #region Properties
4786
4787                 protected override TypeSpec DeclaringType {
4788                         get {
4789                                 return best_candidate.DeclaringType;
4790                         }
4791                 }
4792
4793                 public override string Name {
4794                         get {
4795                                 return best_candidate.Name;
4796                         }
4797                 }
4798
4799                 public override bool IsInstance {
4800                         get {
4801                                 return !IsStatic;
4802                         }
4803                 }
4804
4805                 public override bool IsStatic {
4806                         get {
4807                                 return best_candidate.IsStatic;
4808                         }
4809                 }
4810
4811                 public PropertySpec PropertyInfo {
4812                         get {
4813                                 return best_candidate;
4814                         }
4815                 }
4816
4817                 #endregion
4818
4819                 public override Expression CreateExpressionTree (ResolveContext ec)
4820                 {
4821                         Arguments args;
4822                         if (IsSingleDimensionalArrayLength ()) {
4823                                 args = new Arguments (1);
4824                                 args.Add (new Argument (InstanceExpression.CreateExpressionTree (ec)));
4825                                 return CreateExpressionFactoryCall (ec, "ArrayLength", args);
4826                         }
4827
4828                         args = new Arguments (2);
4829                         if (InstanceExpression == null)
4830                                 args.Add (new Argument (new NullLiteral (loc)));
4831                         else
4832                                 args.Add (new Argument (InstanceExpression.CreateExpressionTree (ec)));
4833                         args.Add (new Argument (new TypeOfMethod (Getter, loc)));
4834                         return CreateExpressionFactoryCall (ec, "Property", args);
4835                 }
4836
4837                 public Expression CreateSetterTypeOfExpression ()
4838                 {
4839                         return new TypeOfMethod (Setter, loc);
4840                 }
4841
4842                 public override string GetSignatureForError ()
4843                 {
4844                         return best_candidate.GetSignatureForError ();
4845                 }
4846
4847                 public override SLE.Expression MakeAssignExpression (BuilderContext ctx, Expression source)
4848                 {
4849                         return SLE.Expression.Property (InstanceExpression.MakeExpression (ctx), (MethodInfo) Setter.GetMetaInfo ());
4850                 }
4851
4852                 public override SLE.Expression MakeExpression (BuilderContext ctx)
4853                 {
4854                         return SLE.Expression.Property (InstanceExpression.MakeExpression (ctx), (MethodInfo) Getter.GetMetaInfo ());
4855                 }
4856
4857                 void Error_PropertyNotValid (ResolveContext ec)
4858                 {
4859                         ec.Report.SymbolRelatedToPreviousError (best_candidate);
4860                         ec.Report.Error (1546, loc, "Property or event `{0}' is not supported by the C# language",
4861                                 GetSignatureForError ());
4862                 }
4863
4864                 bool IsSingleDimensionalArrayLength ()
4865                 {
4866                         if (best_candidate.DeclaringType != TypeManager.array_type || !best_candidate.HasGet || Name != "Length")
4867                                 return false;
4868
4869                         ArrayContainer ac = InstanceExpression.Type as ArrayContainer;
4870                         return ac != null && ac.Rank == 1;
4871                 }
4872
4873                 public override void Emit (EmitContext ec, bool leave_copy)
4874                 {
4875                         //
4876                         // Special case: length of single dimension array property is turned into ldlen
4877                         //
4878                         if (IsSingleDimensionalArrayLength ()) {
4879                                 if (!prepared)
4880                                         EmitInstance (ec, false);
4881                                 ec.Emit (OpCodes.Ldlen);
4882                                 ec.Emit (OpCodes.Conv_I4);
4883                                 return;
4884                         }
4885
4886                         Invocation.EmitCall (ec, InstanceExpression, Getter, null, loc, prepared, false);
4887
4888                         if (leave_copy) {
4889                                 ec.Emit (OpCodes.Dup);
4890                                 if (!IsStatic) {
4891                                         temp = new LocalTemporary (this.Type);
4892                                         temp.Store (ec);
4893                                 }
4894                         }
4895                 }
4896
4897                 public override void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool prepare_for_load)
4898                 {
4899                         Expression my_source = source;
4900
4901                         if (prepare_for_load) {
4902                                 prepared = true;
4903                                 source.Emit (ec);
4904
4905                                 if (leave_copy) {
4906                                         ec.Emit (OpCodes.Dup);
4907                                         if (!IsStatic) {
4908                                                 temp = new LocalTemporary (this.Type);
4909                                                 temp.Store (ec);
4910                                         }
4911                                 }
4912                         } else if (leave_copy) {
4913                                 source.Emit (ec);
4914                                 temp = new LocalTemporary (this.Type);
4915                                 temp.Store (ec);
4916                                 my_source = temp;
4917                         }
4918
4919                         Arguments args = new Arguments (1);
4920                         args.Add (new Argument (my_source));
4921
4922                         Invocation.EmitCall (ec, InstanceExpression, Setter, args, loc, false, prepared);
4923
4924                         if (temp != null) {
4925                                 temp.Emit (ec);
4926                                 temp.Release (ec);
4927                         }
4928                 }
4929
4930                 protected override Expression OverloadResolve (ResolveContext rc, Expression right_side)
4931                 {
4932                         eclass = ExprClass.PropertyAccess;
4933
4934                         if (best_candidate.IsNotRealProperty) {
4935                                 Error_PropertyNotValid (rc);
4936                         }
4937
4938                         if (ResolveInstanceExpression (rc)) {
4939                                 if (right_side != null && best_candidate.DeclaringType.IsStruct)
4940                                         InstanceExpression.DoResolveLValue (rc, EmptyExpression.LValueMemberAccess);
4941                         }
4942
4943                         DoBestMemberChecks (rc, best_candidate);
4944                         return this;
4945                 }
4946
4947                 public override void SetTypeArguments (ResolveContext ec, TypeArguments ta)
4948                 {
4949                         Error_TypeArgumentsCannotBeUsed (ec.Report, "property", GetSignatureForError (), loc);
4950                 }
4951         }
4952
4953         abstract class PropertyOrIndexerExpr<T> : MemberExpr, IDynamicAssign where T : PropertySpec
4954         {
4955                 // getter and setter can be different for base calls
4956                 MethodSpec getter, setter;
4957                 protected T best_candidate;
4958
4959                 protected LocalTemporary temp;
4960                 protected bool prepared;
4961
4962                 protected PropertyOrIndexerExpr (Location l)
4963                 {
4964                         loc = l;
4965                 }
4966
4967                 #region Properties
4968
4969                 public MethodSpec Getter {
4970                         get {
4971                                 return getter;
4972                         }
4973                         set {
4974                                 getter = value;
4975                         }
4976                 }
4977
4978                 public MethodSpec Setter {
4979                         get {
4980                                 return setter;
4981                         }
4982                         set {
4983                                 setter = value;
4984                         }
4985                 }
4986
4987                 #endregion
4988
4989                 protected override Expression DoResolve (ResolveContext ec)
4990                 {
4991                         if (eclass == ExprClass.Unresolved) {
4992                                 var expr = OverloadResolve (ec, null);
4993                                 if (expr == null)
4994                                         return null;
4995
4996                                 if (InstanceExpression != null)
4997                                         InstanceExpression.CheckMarshalByRefAccess (ec);
4998
4999                                 if (expr != this)
5000                                         return expr.Resolve (ec);
5001                         }
5002
5003                         if (!ResolveGetter (ec))
5004                                 return null;
5005
5006                         return this;
5007                 }
5008
5009                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
5010                 {
5011                         if (right_side == EmptyExpression.OutAccess.Instance) {
5012                                 // TODO: best_candidate can be null at this point
5013                                 if (best_candidate != null && ec.CurrentBlock.Toplevel.GetParameterReference (best_candidate.Name, loc) is MemberAccess) {
5014                                         ec.Report.Error (1939, loc, "A range variable `{0}' may not be passes as `ref' or `out' parameter",
5015                                                 best_candidate.Name);
5016                                 } else {
5017                                         right_side.DoResolveLValue (ec, this);
5018                                 }
5019                                 return null;
5020                         }
5021
5022                         // if the property/indexer returns a value type, and we try to set a field in it
5023                         if (right_side == EmptyExpression.LValueMemberAccess || right_side == EmptyExpression.LValueMemberOutAccess) {
5024                                 Error_CannotModifyIntermediateExpressionValue (ec);
5025                         }
5026
5027                         if (eclass == ExprClass.Unresolved) {
5028                                 var expr = OverloadResolve (ec, right_side);
5029                                 if (expr == null)
5030                                         return null;
5031
5032                                 if (expr != this)
5033                                         return expr.ResolveLValue (ec, right_side);
5034                         }
5035
5036                         if (!ResolveSetter (ec))
5037                                 return null;
5038
5039                         return this;
5040                 }
5041
5042                 //
5043                 // Implements the IAssignMethod interface for assignments
5044                 //
5045                 public abstract void Emit (EmitContext ec, bool leave_copy);
5046                 public abstract void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool prepare_for_load);
5047
5048                 public override void Emit (EmitContext ec)
5049                 {
5050                         Emit (ec, false);
5051                 }
5052
5053                 public abstract SLE.Expression MakeAssignExpression (BuilderContext ctx, Expression source);
5054
5055                 protected abstract Expression OverloadResolve (ResolveContext rc, Expression right_side);
5056
5057                 bool ResolveGetter (ResolveContext rc)
5058                 {
5059                         if (!best_candidate.HasGet) {
5060                                 if (InstanceExpression != EmptyExpression.Null) {
5061                                         rc.Report.SymbolRelatedToPreviousError (best_candidate);
5062                                         rc.Report.Error (154, loc, "The property or indexer `{0}' cannot be used in this context because it lacks the `get' accessor",
5063                                                 best_candidate.GetSignatureForError ());
5064                                         return false;
5065                                 }
5066                         } else if (!best_candidate.Get.IsAccessible (rc.CurrentType)) {
5067                                 if (best_candidate.HasDifferentAccessibility) {
5068                                         rc.Report.SymbolRelatedToPreviousError (best_candidate.Get);
5069                                         rc.Report.Error (271, loc, "The property or indexer `{0}' cannot be used in this context because the get accessor is inaccessible",
5070                                                 TypeManager.CSharpSignature (best_candidate));
5071                                 } else {
5072                                         rc.Report.SymbolRelatedToPreviousError (best_candidate.Get);
5073                                         ErrorIsInaccesible (rc, best_candidate.Get.GetSignatureForError (), loc);
5074                                 }
5075                         }
5076
5077                         if (best_candidate.HasDifferentAccessibility) {
5078                                 CheckProtectedMemberAccess (rc, best_candidate.Get);
5079                         }
5080
5081                         getter = CandidateToBaseOverride (rc, best_candidate.Get);
5082                         return true;
5083                 }
5084
5085                 bool ResolveSetter (ResolveContext rc)
5086                 {
5087                         if (!best_candidate.HasSet) {
5088                                 if (rc.CurrentBlock.Toplevel.GetParameterReference (best_candidate.Name, loc) is MemberAccess) {
5089                                         rc.Report.Error (1947, loc, "A range variable `{0}' cannot be assigned to. Consider using `let' clause to store the value",
5090                                                 best_candidate.Name);
5091                                 } else {
5092                                         rc.Report.Error (200, loc, "Property or indexer `{0}' cannot be assigned to (it is read-only)",
5093                                                 GetSignatureForError ());
5094                                 }
5095                                 return false;
5096                         }
5097
5098                         if (!best_candidate.Set.IsAccessible (rc.CurrentType)) {
5099                                 if (best_candidate.HasDifferentAccessibility) {
5100                                         rc.Report.SymbolRelatedToPreviousError (best_candidate.Set);
5101                                         rc.Report.Error (272, loc, "The property or indexer `{0}' cannot be used in this context because the set accessor is inaccessible",
5102                                                 GetSignatureForError ());
5103                                 } else {
5104                                         rc.Report.SymbolRelatedToPreviousError (best_candidate.Set);
5105                                         ErrorIsInaccesible (rc, best_candidate.Set.GetSignatureForError (), loc);
5106                                 }
5107                         }
5108
5109                         if (best_candidate.HasDifferentAccessibility)
5110                                 CheckProtectedMemberAccess (rc, best_candidate.Set);
5111
5112                         setter = CandidateToBaseOverride (rc, best_candidate.Set);
5113                         return true;
5114                 }
5115         }
5116
5117         /// <summary>
5118         ///   Fully resolved expression that evaluates to an Event
5119         /// </summary>
5120         public class EventExpr : MemberExpr, IAssignMethod
5121         {
5122                 readonly EventSpec spec;
5123                 MethodSpec op;
5124
5125                 public EventExpr (EventSpec spec, Location loc)
5126                 {
5127                         this.spec = spec;
5128                         this.loc = loc;
5129                 }
5130
5131                 #region Properties
5132
5133                 protected override TypeSpec DeclaringType {
5134                         get {
5135                                 return spec.DeclaringType;
5136                         }
5137                 }
5138
5139                 public override string Name {
5140                         get {
5141                                 return spec.Name;
5142                         }
5143                 }
5144
5145                 public override bool IsInstance {
5146                         get {
5147                                 return !spec.IsStatic;
5148                         }
5149                 }
5150
5151                 public override bool IsStatic {
5152                         get {
5153                                 return spec.IsStatic;
5154                         }
5155                 }
5156
5157                 public MethodSpec Operator {
5158                         get {
5159                                 return op;
5160                         }
5161                 }
5162
5163                 #endregion
5164
5165                 public override MemberExpr ResolveMemberAccess (ResolveContext ec, Expression left, SimpleName original)
5166                 {
5167                         //
5168                         // If the event is local to this class, we transform ourselves into a FieldExpr
5169                         //
5170
5171                         if (spec.DeclaringType == ec.CurrentType ||
5172                             TypeManager.IsNestedChildOf(ec.CurrentType, spec.DeclaringType)) {
5173
5174                                 // TODO: Breaks dynamic binder as currect context fields are imported and not compiled
5175                                 // EventField mi = spec.MemberDefinition as EventField;
5176
5177                                 if (spec.BackingField != null) {
5178                                         spec.MemberDefinition.SetIsUsed ();
5179
5180                                         if (!ec.IsObsolete) {
5181                                                 ObsoleteAttribute oa = spec.GetAttributeObsolete ();
5182                                                 if (oa != null)
5183                                                         AttributeTester.Report_ObsoleteMessage (oa, spec.GetSignatureForError (), loc, ec.Report);
5184                                         }
5185
5186                                         if ((spec.Modifiers & (Modifiers.ABSTRACT | Modifiers.EXTERN)) != 0 && !ec.HasSet (ResolveContext.Options.CompoundAssignmentScope))
5187                                                 Error_AssignmentEventOnly (ec);
5188
5189                                         FieldExpr ml = new FieldExpr (spec.BackingField, loc);
5190
5191                                         InstanceExpression = null;
5192
5193                                         return ml.ResolveMemberAccess (ec, left, original);
5194                                 }
5195                         }
5196
5197                         if (!ec.HasSet (ResolveContext.Options.CompoundAssignmentScope))
5198                                 Error_AssignmentEventOnly (ec);
5199
5200                         return base.ResolveMemberAccess (ec, left, original);
5201                 }
5202
5203                 public override Expression CreateExpressionTree (ResolveContext ec)
5204                 {
5205                         throw new NotSupportedException ("ET");
5206                 }
5207
5208                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
5209                 {
5210                         if (right_side == EmptyExpression.EventAddition) {
5211                                 op = spec.AccessorAdd;
5212                         } else if (right_side == EmptyExpression.EventSubtraction) {
5213                                 op = spec.AccessorRemove;
5214                         }
5215
5216                         if (op == null) {
5217                                 Error_AssignmentEventOnly (ec);
5218                                 return null;
5219                         }
5220
5221                         op = CandidateToBaseOverride (ec, op);
5222                         return this;
5223                 }
5224
5225                 protected override Expression DoResolve (ResolveContext ec)
5226                 {
5227                         eclass = ExprClass.EventAccess;
5228                         type = spec.MemberType;
5229
5230                         ResolveInstanceExpression (ec);
5231
5232                         if (!ec.HasSet (ResolveContext.Options.CompoundAssignmentScope)) {
5233                                 Error_CannotAssign (ec);
5234                         }
5235
5236                         DoBestMemberChecks (ec, spec);
5237                         return this;
5238                 }
5239
5240                 public override void Emit (EmitContext ec)
5241                 {
5242                         throw new NotSupportedException ();
5243                         //Error_CannotAssign ();
5244                 }
5245
5246                 #region IAssignMethod Members
5247
5248                 public void Emit (EmitContext ec, bool leave_copy)
5249                 {
5250                         throw new NotImplementedException ();
5251                 }
5252
5253                 public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool prepare_for_load)
5254                 {
5255                         if (leave_copy || !prepare_for_load)
5256                                 throw new NotImplementedException ("EventExpr::EmitAssign");
5257
5258                         Arguments args = new Arguments (1);
5259                         args.Add (new Argument (source));
5260                         Invocation.EmitCall (ec, InstanceExpression, op, args, loc);
5261                 }
5262
5263                 #endregion
5264
5265                 void Error_AssignmentEventOnly (ResolveContext ec)
5266                 {
5267                         ec.Report.Error (79, loc, "The event `{0}' can only appear on the left hand side of `+=' or `-=' operator",
5268                                 GetSignatureForError ());
5269                 }
5270
5271                 public void Error_CannotAssign (ResolveContext ec)
5272                 {
5273                         ec.Report.Error (70, loc,
5274                                 "The event `{0}' can only appear on the left hand side of += or -= when used outside of the type `{1}'",
5275                                 GetSignatureForError (), TypeManager.CSharpName (spec.DeclaringType));
5276                 }
5277
5278                 protected override void Error_CannotCallAbstractBase (ResolveContext rc, string name)
5279                 {
5280                         name = name.Substring (0, name.LastIndexOf ('.'));
5281                         base.Error_CannotCallAbstractBase (rc, name);
5282                 }
5283
5284                 public override string GetSignatureForError ()
5285                 {
5286                         return TypeManager.CSharpSignature (spec);
5287                 }
5288
5289                 public override void SetTypeArguments (ResolveContext ec, TypeArguments ta)
5290                 {
5291                         Error_TypeArgumentsCannotBeUsed (ec.Report, "event", GetSignatureForError (), loc);
5292                 }
5293         }
5294
5295         public class TemporaryVariable : VariableReference
5296         {
5297                 LocalInfo li;
5298
5299                 public TemporaryVariable (TypeSpec type, Location loc)
5300                 {
5301                         this.type = type;
5302                         this.loc = loc;
5303                 }
5304
5305                 public override Expression CreateExpressionTree (ResolveContext ec)
5306                 {
5307                         throw new NotSupportedException ("ET");
5308                 }
5309
5310                 protected override Expression DoResolve (ResolveContext ec)
5311                 {
5312                         eclass = ExprClass.Variable;
5313
5314                         TypeExpr te = new TypeExpression (type, loc);
5315                         li = ec.CurrentBlock.AddTemporaryVariable (te, loc);
5316                         if (!li.Resolve (ec))
5317                                 return null;
5318
5319                         //
5320                         // Don't capture temporary variables except when using
5321                         // iterator redirection
5322                         //
5323                         if (ec.CurrentAnonymousMethod != null && ec.CurrentAnonymousMethod.IsIterator && ec.IsVariableCapturingRequired) {
5324                                 AnonymousMethodStorey storey = li.Block.Explicit.CreateAnonymousMethodStorey (ec);
5325                                 storey.CaptureLocalVariable (ec, li);
5326                         }
5327
5328                         return this;
5329                 }
5330
5331                 public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
5332                 {
5333                         return Resolve (ec);
5334                 }
5335
5336                 public override void Emit (EmitContext ec)
5337                 {
5338                         Emit (ec, false);
5339                 }
5340
5341                 public void EmitAssign (EmitContext ec, Expression source)
5342                 {
5343                         EmitAssign (ec, source, false, false);
5344                 }
5345
5346                 public override HoistedVariable GetHoistedVariable (AnonymousExpression ae)
5347                 {
5348                         return li.HoistedVariant;
5349                 }
5350
5351                 public override bool IsFixed {
5352                         get { return true; }
5353                 }
5354
5355                 public override bool IsRef {
5356                         get { return false; }
5357                 }
5358
5359                 public override string Name {
5360                         get { throw new NotImplementedException (); }
5361                 }
5362
5363                 public override void SetHasAddressTaken ()
5364                 {
5365                         throw new NotImplementedException ();
5366                 }
5367
5368                 protected override ILocalVariable Variable {
5369                         get { return li; }
5370                 }
5371
5372                 public override VariableInfo VariableInfo {
5373                         get { throw new NotImplementedException (); }
5374                 }
5375         }
5376
5377         ///
5378         /// Handles `var' contextual keyword; var becomes a keyword only
5379         /// if no type called var exists in a variable scope
5380         ///
5381         class VarExpr : SimpleName
5382         {
5383                 // Used for error reporting only
5384                 int initializers_count;
5385
5386                 public VarExpr (Location loc)
5387                         : base ("var", loc)
5388                 {
5389                         initializers_count = 1;
5390                 }
5391
5392                 public int VariableInitializersCount {
5393                         set {
5394                                 this.initializers_count = value;
5395                         }
5396                 }
5397
5398                 public bool InferType (ResolveContext ec, Expression right_side)
5399                 {
5400                         if (type != null)
5401                                 throw new InternalErrorException ("An implicitly typed local variable could not be redefined");
5402
5403                         type = right_side.Type;
5404                         if (type == InternalType.Null || type == TypeManager.void_type || type == InternalType.AnonymousMethod || type == InternalType.MethodGroup) {
5405                                 ec.Report.Error (815, loc,
5406                                         "An implicitly typed local variable declaration cannot be initialized with `{0}'",
5407                                         type.GetSignatureForError ());
5408                                 return false;
5409                         }
5410
5411                         eclass = ExprClass.Variable;
5412                         return true;
5413                 }
5414
5415                 protected override void Error_TypeOrNamespaceNotFound (IMemberContext ec)
5416                 {
5417                         if (RootContext.Version < LanguageVersion.V_3)
5418                                 base.Error_TypeOrNamespaceNotFound (ec);
5419                         else
5420                                 ec.Compiler.Report.Error (825, loc, "The contextual keyword `var' may only appear within a local variable declaration");
5421                 }
5422
5423                 public override TypeExpr ResolveAsContextualType (IMemberContext rc, bool silent)
5424                 {
5425                         TypeExpr te = base.ResolveAsContextualType (rc, true);
5426                         if (te != null)
5427                                 return te;
5428
5429                         if (RootContext.Version < LanguageVersion.V_3)
5430                                 rc.Compiler.Report.FeatureIsNotAvailable (loc, "implicitly typed local variable");
5431
5432                         if (initializers_count == 1)
5433                                 return null;
5434
5435                         if (initializers_count > 1) {
5436                                 rc.Compiler.Report.Error (819, loc, "An implicitly typed local variable declaration cannot include multiple declarators");
5437                                 initializers_count = 1;
5438                                 return null;
5439                         }
5440
5441                         if (initializers_count == 0) {
5442                                 initializers_count = 1;
5443                                 rc.Compiler.Report.Error (818, loc, "An implicitly typed local variable declarator must include an initializer");
5444                                 return null;
5445                         }
5446
5447                         return null;
5448                 }
5449         }
5450 }